Tomorrow's Citations
Architecture Development


The objective is to derive a convenient architecture for citations and references in online documents that promotes evidence-based communication on the Internet and is broadly applicable beyond research environments. Exploration of this objective has led to the identification of thirty citation-based communication needs. These needs have motivated the development of a new citation architecture.


A reader is someone who views Internet content. A reader need is anything that helps readers assess and absorb content.

Contributors are people involved in creating, presenting, and maintaining content, including any research involved in creating content. Contributors are conveniently divided into content creators and secondary contributors. Authors are content creators who accept responsibility for content.

A contributor need is anything that contributes to the successful creation, organization, and presentation of content to readers. Contributor needs in this sense may differ from requirements imposed by publishers.

We will be discussing a citing document's citations and references. In-text citations occur in the citing document's main text. Its references occur in its reference section (works cited section). The combination of an in-text citation and the reference it points to is a citation. A reference points to cited content. Typically, the cited content is on a web page that also includes uncited content — advertisements, for example.

A hyperlink either points to an entire document with a full-document URL or to an portion of the cited document with a fragment URL. An HTML link target is the point in the document that a URL points to. A citation can point to an image, to a document or document fragment, or to ay other element that a URL can point to..


This work addresses five questions.

  1. What guidance is provided by existing style guides?
  2. What communication needs are addressed by this guidance?
  3. What additional needs exist in the online environment?
  4. What citation and reference formats address the needs of readers and contributors?
  5. How can we automatically bridge the gap between the resulting reader and contributor formats?

The first two questions have to do with existing style guides. Question 3 moves beyond existing guidance to address additional communication needs.

 Answers to Questions 2 and 3 provide 30 insights into the nature of citation-related communication needs. These identified needs show how to fulfill the requests made in Question 4. Unfortunately, these requests produce different results for readers and content creators. Question 5 asks how to bridge the gap between the resulting reader and contributor formats.

1. Existing Guidance  

The following style guides were selected for study:

In addition to studying these guides, we will also look briefly at bibliographies and at the Zotero citation-generating tools[zotero].

The order of the elements in these guides differs but the topics covered are largely the same. However, the organization of the guides varies significantly.

The NLM guide splits immediately into 25 chapters covering individual cases — books, journals, databases, and so forth. The NLM stands alone in not devoting any chapters to general principles.

The Chicago guide covers 100 general points before breaking out into special cases — books, journals, and so forth.

In the APA guide, references are broken out into four main elements and each is discussed prior to getting into special cases — religious works, works in a foreign language, and so forth.

The main body of the MLA guide is devoted entirely to general principles. Special cases are relegated to a voluminous Appendix 2.


The selected guides provide four basic approaches to in-text citations:.

Author, date, and page range. The APA syntax looks like this: (Henry 2014, p. 14)[APA, citation]. The Chicago author-date system looks like this: (Henry 2014, 14)[comes, author-date]. The NLM also mentions a similar name-year system in its introduction[NLM, intro].

Author and page range. The MLA syntax looks like this: (Henry 14)[MLA, citation-guide].

Citation number and page range. The Chicago notes-and-bibliography system uses in-text superscripts along with footnotes that can provide page ranges[comes, note-bibliography].

Citation number. The NLM citation-sequence system uses a numeric superscript: 1. So does the NLM citation-name system[NLM, intro].

References — Uniqueness

The extensive detail in the APA, MLA, and Chicago style guides results in an interesting uniqueness property. Within a given style, two references to the same work will in most cases be identical — identical list of author names, identical titles and edition designations, identical named publishers, identical date designations, and so forth. This uniqueness property doesn't quite hold for the NLM style because it allows for many optional fields in its references.

Authors, Roles, and Affiliations

Guidance on how many authors to list varies significantly. The NLM says to try to list every author[NLM, authors-article]. The APA says to list up to twenty authors[APA, authors]. The Chicago guide says up to ten[comes, authors]. The MLA says list up to two[MLA, authors].

Interestingly, in the guides selected for study, if a referenced document fails to specify authorship, the author element is simply omitted. This convention differs, for example, from date elements where missing information is explicitly noted as "n. d."

All four guides provide for secondary contributor roles. Role names always follow contributor names[NLM, contributors][comes, contributors][APA, roles][MLA, author-roles]. However, only a limited set of roles is mentioned, primarily the author, editor, illustrator, and translator roles. The MLA goes farther, listing conductor, creator, director, narrator, and performer as additional roles[MLA, author-roles].

The NLM guide asks for authors' institutional affiliations[NLM, affiliation-books][NLM, affiliation-articles][NLM, affiliation-web-pages].

Personal Communications

The guides are mainly silent on how to cite personal communications. The NLM says to mention recipients when referencing emails[NLM, email]. The APA guide says to mention personal communications only in the main text if readers do not have a way of accessing them[APA, personal]. The Chicago style says to treat the recipient as part of the title when a personal communication is listed in the bibliography[comes, personal]. Zotero says to list email recipients as contributors having a recipient role[zotero, recipient].

Titles, Portions, and Editions

All guides provide for giving the title's Language if it is not in English and giving an English translation, in effect providing two titles in this case.

The guides provide conventions for titling a portion of a more extensive work — for example, an article section. In the NLM, a reference to a perceived whole usually precedes the reference to the part[NLM, article-part] but not always[NLM, listservs]. The MLA says to cite the part first[MLA, parts]. The APA says to cite only the parent document because that is what readers would retrieve to find the part[APA, citation]. The Chicago style places the chapter title before the book title[comes, chapter].

Some guides provide for title clarifications. In the APA guide, the clarification is placed in square brackets following the title. Typical clarifications are Abstract, Conference Presentation, Conference Presentation Abstract.

The MLA considers the case of nested containers where one text is contained in a larger body of work which may be contained in a third[MLA, containers]. It gives a dozen container examples[MLA, figure-5.29].

Titles are often accompanied by edition/version information. Examples include the weekend edition, revised edition, British edition, sixth edition. Version designations immediately follow the title[NLM, book-edition][MLA, version]. Similar auxiliary information occurs in connection with journals[NLM, date-augmentation][NLM, volume-augmentation][NLM, issue-augmentation][APA, edition]. References to newspaper articles may include a column number; a section letter, number, or name; a part title; or a page range[NLM, newspaper].


Guidance varies as to whether to include the publisher's city. The MLA says to include the city only if the book was published before 1900[MLA, 1900].

In addition to traditional book publishing houses, there are several variants.

Newspapers: Substitute the name of the newspaper for the publisher[NLM, newspaper].

Journal articles: Substitute the name of the journal.

Web pages: Substitute the page's website[NLM, website-publisher][APA, web-page-reference]. Substitute the title and owner of the web page's website[comes, websites][comes, citing-websites]. Substitute the website's title[MLA, containers].

In each of these variants, the guides invariably use the name of the publication as a stand-in for the names of the publication's editors.

A publication can have multiple publishers, and a publisher's name can change over time. The Chicago guidance is to use the name of the publisher of the work at the time it was published[comes, publisher].


All style guides provide for the date of the last update or revision as well as a publication date. The NLM style also requires the date when an author most recently accessed the referenced page[NLM, accessed-date]. The APA guide also includes this requirement under various circumstances[APA, retrieval-date]. Secondary guidance includes examples of dates that do not merit inclusion.


There is a fair amount of variation. The NLM advises the use of permalinks. Several guides advise using DOIs in place of URLs. Only the NLM guide entertains the possibility of providing more than one URL for a source. It suggests using either one or else all available URLs[NLM, URLs-books][NLM, URLs-journals][NLM, URLs-databases].


The Chicago style specifically calls out eBooks as requiring additional attention because special software is needed to read them[comes, online-formats].

Content Type

The NLM style provides for an optional "content type" or "article type"[NLM, article-type-journal][NLM, content-type-book][NLM, content-type-bibliography]. Some of the examples are about content, while others are about how it is presented. Content examples include book review, editorial, interview, demographic map, and bibliography. Presentation examples include poster, email, letter, and conversation. Notes

The NLM guide includes a notes section used to indicate error notices, retractions, epub dates, accompanying auxiliary materials, and so forth[NLM, notes-books][NLM, notes-reports].


Webliography references differ substantially from what the guides call for. The most familiar bibliographies are those produced automatically by search engines. Google News provides attractive curated bibliographies. Website home pages sometimes include bibliographies that present the site's principal web pages. Since bibliographies are not from the ink-and-paper world, they offer insights into how the reference concept will evolve.

All bibliographies contain a title and a link to the referenced page. They normally include a description of the page's content. They may also have a favicon calling attention to the publisher, hosting website, or the page's corresponding root page. Favicons are the small icons seen at the top of browser tabs in a web browser. Webliographies sometimes include an image indicative of the page's content. The most common ordering of webliography elements is this:

Notice that the first two required elements are the title and a link to the referenced page. Webliographies include annotations because they are stand-alone documents; in-text citations are not available to stimulate interest in webliography entries.

The Zotero tools

 The Zotero architecture may be conveniently described using database concepts. (Although this is not how Zotero describes itself.) Zotero consists of a database design, virtual Zotero databases, routines for viewing database entries, tools for importing entries into user libraries, and editor plugins to integrate local database entries into user documents.

The Zotero database design takes the place of a style guide. It specifies the fields that can be populated by a citation stored in a Zotero virtual database or library. The design supports five general fields and many variant fields depending on the citation's item type. These are the general fields[zotero, data-design]:

Citation Key — the field that will become the link between an in-text citation and its corresponding reference entry.
Creators — authors and other content creators and contributors
Title — a title stored in sentence-case format
Date — separate fields for month, day, and year
Item Type — 38 types (e.g., book, journal article)

The Zotero tools can map online document collections to virtual Zotero databases. For example, the PubMed articles have a Zotero view.

Rendering routines can display a Zotero database entry in any of 10,000 citation styles[zotero, styles], including any of the four styles selected for this study.

Local collections are maintained on a user's computer in the user's Zotero library. Entries in the user's library can be tailored, for example, if a citation's title casing must differ from that calculated by Zotero..

Chrome and Safari Zotero browser extensions allow the following: Browse to an online document with a supported Zotero view, a PubMed abstract, for example. Clicking on a button imports the document's Zotero entry into a user's local library.

Software plugins to word processors such as Word, LibreOffice, and Google Docs allow a user to enter a citation via its citation key. The Zotero editor extension adds the corresponding reference in a user-specified citation style and replaces the citation key with a proper citation.

One thing that is not yet supplied by the Zotero architecture is an HTML Zotero meta tag that allows a web author to straightforwardly specify a web page's Zotero database entry. What seems to be needed is a universal Zotero citation style that can display any element of the Zotero database along with a Zotero meta tag that accepts any Zotero citation. The Zotero browser extension would then create a Zotero database entry for any web page containing a well-formed Zotero meta tag.

2. Needs Addressed  

Little has been published on needs addressed by the existing guidelines aside from avoiding plagiarism. So this question is answered by inference from the guidance provided.

From an author's perspective, the purpose of references is to show how the author's work builds on what went before. The not-so-subtle subtext is that "These people have done great work, and this author's work is in league with theirs." To buy this line of thought, the reader must trust the cited work and grasp its relevance to the citing document. Consequently, this analysis of needs focuses largely on matters of trust and relevance.

Needs Related to Citations

All of the studied styles meet the need to link in-text citations and references. But they vary with regard to other needs.

Need 1. In-text citations need to avoid interfering with reading the main text.

The numeric superscript citations excel in this regard, as does the Chicago notes-and-bibliography system. However, the NLM citation-sequence system complicates the authoring process. To add a new reference that's needed somewhere in the middle of the citing document, an author must renumber all later citations and their corresponding references.

Notice that there is already a conflict between contributor and reader needs. The NLM superscripts address a reader need at the expense of complicating the authoring process.

Need 2. An in-text citation needs to remind the reader of its cited reference.

A citation that includes an author's name may remind the reader of which reference is being cited. The footnotes of the Chicago notes-and-bibliography system have excellent mnemonic value. By contrast, the NLM citation-sequence system has no mnemonic value. The curated presentations put out by PubMed correct for this NLM deficiency by showing the corresponding reference whenever the reader mouses over a citation[pubreader]. These NCBI reference notes take the place of the notes in the Chicago notes-and-bibliography system. Wikipedia[wikipedia] also has mouseover reference notes with minor variations in terminology and behavior via toolltips[wiki-tooltip], reference previews[wiki-preview], and reference overlays[wiki-overlay].

Notice that automation is already at work in reconciling the conflicting needs of contributors and readers.

Need 3. Citations need to be able to cite page ranges.

Each of the non-numeric citation styles provides a way to include page ranges in the citation. The Chicago notes-and-bibliography style stands alone in providing both numeric superscripts and a way to specify page ranges.

The NLM des not provide for including page numbers in in-text citations. Page numbers must instead include the page information in the reference section.

Needs Related to Reference Sections

Of the needs relating to references, three have to do with the overall organization of references. Eleven more have to do with specific reference elements.

Need 4. There needs to be a strongly defensible ordering of the reference elements.

The guides studied differ in their ordering of reference elements. For example, the date element comes second in the APA style, whereas it comes near the end in the other styles.

In the NLM guide, reference elements of primary interest to the reader are scattered in various locations. The title is the 8th element, and URLs are the 17th. But, judging from the webliography styles, these are the essential elements. Title-related elements are not necessarily placed together. For example, a part number may follow the date rather than the title[NLM, date-augmentation]. Booksellers place title-related information directly after the title.

Which reference element to list first? In the bibliographies, it's the title. The title is also the first element in the PubMed mouseover notes, even though the author comes first in the corresponding article reference.

Need 5. There needs to be a simple, consistent approach to punctuation.

As the IEEE guidance put it: "All punctuation, dates, and page numbers depend on the type of reference cited, so follow the examples with care."[IEEE] The APA straightforwardly requires that most elements in a reference end with a period[APA, punctuation].

Need 6. There is no pressing need for abbreviations.

All of the studied guides provide detailed guidance on abbreviations. The NLM, for example, devotes five appendices to the subject. This may have made sense for print documents because paper is incomparably more expensive than bits and bytes. But extensive use of abbreviations can distract from readability, and finding the approved abbreviation for a term can be time consuming.

Need 7. There needs to be flexibility in the number of authors to list in a reference.

How many authors should be listed? Up to two, up to ten, up to nineteen, or perhaps every author? Is there any objective evidence showing that historians, psychologists, and medical researchers legitimately differ in how many authors they need to see? Perhaps. Medical research papers are often too obscure to attract a broad audience. So the likely readership of the citing document may well consist largely of the authors of the referenced articles. In this case, listing every author makes sense.

Need 8. There need to be additional provisions for referencing subsidiary content.

Existing citation guidance recognizes subsidiary content in at least two cases. Page ranges are subsidiary to the book. Individual works are subsidiary to the anthology. But none of the cited styles provide for citing portions of web pages. There is no reason to assume that a reader's interest in specific content found on a web page implies an interest in other co-occurring content on the same page.

In online documents, there are five evident methods for handling subsidiary content:

Page ranges and fragment links both describe portions of a referenced document. Fragment links and subsidiary-document links both take the reader directly to presentations of subsidiary content.

A document may be included only to amplify another document already in the reference section. Examples include cases where one document is an abstract for, a critique of, a comment on, an error report for, or an advertisement for the sighted document.

Need 9. Additional ways of documenting author credibility are needed.

The ability to assess author credibility is essential to the goal of supporting evidence-based communication.

The NLM guide specifies the inclusion of an author affiliation. This requirement may assist in judging the credibility of authors in a research environment. However, in a world with 28 million web developers[galov] and many more content creators, an institutional affiliation is not a reliable indication of author credibility.

Need 10. The treatment of personal communications needs to be addressed.

The APA guide says not to cite personal communications unless they have a citable source[APA, personal]. However, some personal communications do have independent confirmation, as in the case of an 1803 letter from Thomas Jefferson to James Madison[jeff-letter]. In addition, genealogies often contain personal letters that get posted online. An answer to Question 1 notes the need to specify email recipients when referencing emails. The approach used in Zotero is to treat the recipient as a secondary item creator[zotero, recipient].

Need 11. The publishing concept is in need of generalization. Self-published material needs to be clearly identified.

To carry the publisher concept forward into an online world, we must ask what constitutes an act of publishing. An answer to Question 1 notes that news papers, journals, and websites can all substitute for publishers in references. What do these examples have in common?

Public libraries distribute content to the public but do not publish; they often have an online presence, as with the Library of Congress. YouTube, Twitter, and Reddit provide platforms for unedited contributions, which they also do not publish. Used book stores do not publish. What do these examples lack?

Newspapers and journals publish in the above sense. These examples suggest that it is appropriate for a reference to designate as publishers the institutions that carry out the above-described publishing functions. For example, the publishing function for The Brave by Nicholas Evans[brave] was performed by G. P. Putnam's Sons, which is an imprint of the Penguin Random House publisher[putnam]. The need addressed by knowing who performs the publishing function is for the reader to better understand the published information's validity.

What remains is the issue of who publishes online content. The guides studied tend to assume that content found on a web page is published by the page's website, even if the content was published a hundred years ago, as in the case of Charles Dickens' A Christmas Carol[dickens]. The usual guidance is to use the website's title in place of a traditionally recognized publisher. The NLM differs in requiring what is essentially a complete reference for the page's website. And the MLA asks for the website's publisher, though there is no evidence that the site's publisher is actively involved in publishing cited content. The publishing function for a web page needs to be identified according to the above three publishing criteria.

At issue is the fact that the Web holds great quantities of self-published material. Facebook posts and Twitter tweets are essentially self-published.The document-review function i typically limited to censoring objectionable content.  Personal websites are frequently devoted to self-published material.

Need 12. In the case of a work with multiple publishers, the most important one is the publisher that had the most to do with the work's credibility. Typically, the publisher most involved in bringing a work to fruition is the one that is most relevant to the work's credibility. There needs t be a concept of principal publisher..

Need 13. The date of a document's content is more relevant than the date of the document.

In the print world, a reference lists a book's publication date rather than the date of the book's nth printing. The same discrepancy can exist for online documents.  For example, an appropriate publication date for A Christmas Carol might be 1911[dickens]. The date when the Library of Congress acquired an online copy is less relevant to understanding that novel's credibility. However, in some cases, the date of a web page can be a fair estimate of the date of its primary content.

Need 14. Dates that are not properties of the document itself are not relevant.

A notable example of an irrelevant date is the date when an author accessed a document:

Need 15. Permalinks are more important than DOIs.

DOIs are not interpreted by web browsers. They require an extra translation step. To translate a DOI to a URL, prepend the DOI with[DOI-article].

Many organizations prefer to develop their own systems of permalinks, perhaps due in part to cost. The new guide needs to give more examples of how organizations handle permalinks. A notable example of an organization that makes do without permalinks is the Library of Congress - content  displayed to the public is subject to change.

Need 16. Reader convenience demands the use of hyperlinks .

When the Internet was young, URLs tended to be readable, typable, and less than one line in length, but none of this tends to be true today. The only common use of URLs is to follow them to the documents they point to. A reader who wants the actual URL can always use the browser's "copy link" feature.

Need 17. The new guide's handling of version, volume, issue, and similar "appendage" information needs to be simple.

Classifying articles by volume, issue, and page range is relevant to finding articles in the library stacks, but not so much online.

There is also less need for advertised versions. Why? Before the Internet, digital information was printed on physical media and went through advertised versions in much the same way as print documents. Then in 1991, Tim Berners-Lee introduced the World Wide Web[WWW]. It soon became a royal highway for malware and other malevolent content. In response, vendors now release frequent updates distributed over the Internet without fanfare, making the release of advertised versions and editions less frequent than was once the case.

Summary List of Needs

  1. In-text citations need to avoid interfering with reading the main text.
  2. An in-text citation needs to remind the reader of its cited reference.
  3. Citations need to be able to cite page ranges.
  4. There needs to be a strongly defensible ordering of the reference elements.
  5. There needs to be a simple, consistent approach to punctuation.
  6. There is no pressing need for abbreviations.
  7. There needs to be flexibility in the number of authors to list in a reference.
  8. There need to be additional provisions for referencing subsidiary content.
  9. Additional ways of documenting author credibility are needed.
  10. The treatment of personal communications needs to be addressed.
  11. The publishing concept is in need of generalization. Self-published material needs to be clearly identified.
  12. In the case of a work with multiple publishers, the most important one is the publisher that had the most to do with a referenced work's credibility.
  13. The date of a document's content is more relevant than the date of the document.
  14. Dates that are not properties of the document itself are not relevant.
  15. Permalinks are more useful than DOIs.
  16. Reader convenience demands the use of hyperlinks.
  17. The new guide's handling of version, volume, issue, and similar "appendage" information needs to be simple.

3. Additional Needs  

This section identifies 13 additional needs that must be addressed to provide a broadly applicable reference architecture that supports evidence-based communication.

Need 18. The new guide is to be organized around simple general principles.

It is easier to learn a general principle than to learn many special cases, even if the general principle has exceptions. This is true even if it is necessary to introduce new terminology to state the general principle. These facts call for a uniform approach to such things as syntax, for example.

Three of the four studied guides appeal to general principles. The exception is the NLM guide.

Need 19. The new guide needs too omit requirements for which there is no pressing rationale.

The first sentence of this document lists the goal of being widely applicable beyond research communities. Consequently, the new guide needs to be easy to use by content creators who have little or no experience writing citations and references. This need strongly affects what does not go into the new guide.

Any decision that can be safely left to authors does not belong in the guide.

The study of existing guidance established that, in most cases, a reference is uniquely determined by the document referred to. This is even true of entries retrieved from Zotero collections such as PubMed. Going forward, this uniqueness could be true for arbitrary web pages if there were, say, a Zotero template that a web author could provide in the form of a Zotero meta tag.

Need 20. References need to clearly delineate the reader's twin goals of assessing whether referenced content is of interest and whether there is a danger of being misled.

As stated at the beginning of the previous section, the purpose of a reference is to show how the author's work builds on what went before. Success depends on whether the reader trusts the cited work and grasps its relevance to the citing document.

Need 21. The new guide needs to support the inclusion of honorific titles and author biographies.

Honorific titles such as Ph.D., MD, or LCSW help readers to assess author credibility[schema, honorific-suffix ]. For example, an author of an article on effective marriage counseling might be an LMFT.

An emerging trend in online articles is to provide a bio. Having a biography helps to assess the authors' credibility. Bios can also make for enjoyable reading. There needs to be provision for including links to bios.

Need 22. A reference needs to be about referenced content, as opposed to presentations of content.

The same content can have many different presentations. This is especially true on the Internet where the same article may be formatted differently on different devices or on different websites. So a guide that relates to content can be more useful than a guide that pertains solely to presentation.

From the perspective of evidence-based communication, original documents do have some additional claim to credibility. But outside of a research environment, there is relatively little interest in original sources. For example, it is generally agreed that  E   mc2 even though few have read Einstein's famous paper[einstein].

Need 23. There is a need for additional structure in reference sections.

Imagine a paper that consisted of fifty one-sentence paragraphs. Nobody writes this way. But that's precisely what one sees in a traditional reference section. Such an organization provides a disincentive to reading reference sections. This is a reader need rather than a contributor need.

Need 24. Improving the visual appeal of a reference section increases its usefulness by increasing its probability of being read.

Readers of web content rely heavily on visual appeal in judging a website's credibility[credibility1][credibility2].

Color is a crucial aspect of visual appeal. The importance of color can be judged by looking at how it has influenced other areas of communication. Color TV became popular in the 1960s[color-TV]. Color in newspapers became popular in the 1980s[color-news]. Favicons add color to web browsers. Bharat Shyam invented them as a last-minute addition to Internet Explorer 5 tabs in 1999[favicon][ie5].

Need 25. A convenient way to get from a citation to its corresponding reference is to follow a hyperlink. This works for citations that reference an entire document and for citations that point to an anchored place in a document. An additional mechanism is needed for citations that reference non-anchored locations in a document.

Hyperlinks from in-text citations to references accomplish the main purpose of citations, which is to associate a reference with a particular spot in the main text. From this perspective, all that is needed is to place a mark in the main text and hyperlink it to the cited reference.

Need 26. The new guide needs to clearly distinguish between online documents that are directly available to readers and documents that are merely available online, as in the case of documents that are available for purchase. That is to say, the new guide needs to distinguish between links that point directly to referenced material and links that connect to referenced material.

The guide Citing Medicine is directly available[NLM]. The Chicago Manual of Style, though not directly available, does have directly available URLs[comes]. The Publication Manual of the American Psychological Association is available as an eBook[APA]. The MLA Handbook 9th is available as a Kindle eBook[MLA]. The NLM and Chicago guides may be treated as directly available for purposes of referencing. The other two guides may not.

In addition to hyperlinks that point to directly available content, there are other links that connect to  reviews, abstracts, corrections, clarifications, and addenda to a referenced work. These connections are important for offline documents because there may be no hyperlink to the documents themselves. There needs to be a way to distinguish between direct links and connecting links..

Need 27. A reference may need author-supplied clarification for various reasons.

This need is alluded to already in the NLM notion of a content type. A reference may need clarification in either of the following ways:

Format: Some readers avoid PDF files or Power Point documents.

Content: It helps to know whether a referenced work is a book review, clinical trial, consensus document, exposition, large-scale study, literature review, news article, abstract, and so forth.

Need 28. Several links may be needed for the same reference. The most credible link needs to be given first. There are several reasons for allowing a reference to have multiple links.

Impermanence. A post that has gone viral may have a lengthy persistence even though its persistence in any given location is far from assured. The urgency of this need has been documented by Susan Herring:

Almost 18 percent of the electronic resources cited in the articles analyzed either were not found or could not be accessed[Herring].

Access Cost. Availability may hinge partly on the reader's wealth or influence — an article that's free to professors may cost $60 to others. In many cases, a free abstract contains all the information a reader needs.

Language Barrier. If the same work is published in several languages, several URLs may be needed to achieve the desired availability.

Need 29.There needs to be a way of referencing content in the cited document even where its authors didn't think to provide bookmarks.

The authors of the citing document usually have no control over where authors of the cited document think to provide bookmarks. Some documents have plenty of bookmarks. The NLM guide is an excellent example here. At the opposite extreme are offline documents which contain no bookmarks even after they've been scanned in and converted to documents that are available online. Three of the four guides make explicit provision for citing material that occurs at arbitrary places in the cited document.

Most guides allow citing arbitrary pages in the cited document . The NLM guide is deficient in this regard.

Need 30. The new guide needs to honor the fact that there are potentially many different roles in the authoring process.

An answer to Question 1 notes that the studied guides mentioned only a limited set of author roles. Having enough roles to accurately describe authors and other contributors is central to the use of roles in assessing author credibility.

The relative lack of roles in the studied guides conflicts with other guidance on user roles. The CRediT project has identified fourteen contributor roles related to scientific, scholarly output[cr, CRediT1]. Matthew Childers has described roles that are prominent in the creation of movies and comic books. His article convincingly illustrates the distinction between roles and role names[Childers].[schema] identifies some contributor roles[schema, role]. So does the U.S. patent office[patents]. IOP Publishing discusses five authoring roles associated with scientific research[IOPScience]. The International Committee of Medical Journal Editors mentions roles in addressing the distinction between author and non-author contributors[ICMJE]. The Zotero tools recognize roles referred to as item creators[zotero, item-creators]. Putting these sources together leads to the following list of contributor roles:

content creators
Secondary Contributors

Summary List of Needs Continued

  1. The new guide is to be organized around simple general principles.
  2. The new guide omits requirements for which there is no pressing rationale.
  3. References need to clearly delineate the reader's twin goals of assessing whether referenced content is of interest and whether there is a danger of being misled.
  4. The new guide needs to support the inclusion of honorific titles and author biographies.
  5. A reference needs to be about referenced content, as opposed to referenced representations of content.
  6. There is a need for additional structure in reference sections.
  7. Improving the visual appeal of a reference section increases its usefulness by increasing its probability of being read.
  8. A convenient way to get from a citation to a corresponding reference is to follow a hyperlink.
  9. The new guide needs to distinguish between links that point directly to referenced material and links that merely establish connections to the referenced material.
  10. A reference may need author-supplied clarification for various reasons.
  11. Several links may be needed for the same reference. The most credible link needs to be given first.
  12. There needs to be a way for links to point to unlabeled material.
  13. The new guide needs to honor the fact that there are potentially many different roles in the authoring process.

4. Architecture

We are now at the point of designing an architecture who's complexity is commensurate with the needs of readers and content creators. The need for simplicity and learnability demands a strong emphasis on uniform structure and general principles. Our tasks are to design

The following subsections have an alternating paragraph structure. A paragraph recalls needs that answer Questions 2 and 3. Then an indented paragraph presents the resulting guidance.


Need 3 notes a tension between the need to cite subsidiary content and the need to not interfere with the readability of the main text. It notes the superiority of the Chicago notes-and-bibliography system in this regard. Need 2 notes that PubMed's mouseover notes serve a similar purpose to Chicago notes. Need 8 alludes to the fact that there are at least three significant ways in which one referenced work can be subsidiary to another. The subsidiary portion could be a page range, a named section, or another page.

Citations and URLs may be classified according to where they point. A citation that points to a point that isn't a target point can be specified by giving a URL and then naming a fragment of the range that is given by a page number or the paragraph count starting with the link target. Another approach is to quote a key identifying phrase.

Citations can point to references in one of two ways.

A root citation identifies content that, within the context of the citing document, is not part of some larger cited body of work.

A subsidiary citation identifies content that is logically subsidiary to content that is identified by a root citation.

The organization of cited content into root content and subsidiary content is performed at the discretion of the content creators. The subsidiary content may be found in a section of the cited root document, another document, or a section of another document. The other document may have an unrelated URL.

To resolve the discrepancy between authoring needs and reader needs, each of these citation ways has both an author view and a reader view. The author view has to be machine parsable.

A root citation in the author view has the form \[root], where the root identifier is chosen at the convenience of content creators. A subsidiary citation has the form \[root, part-name], where the part-name is a short name for the subsidiary content. To prevent a bracketed passage from being treated as a citation, escape its left bracket with a back slash, like so: \\[ not-a-citation ].

The contributor-to-reader transformation transforms a each citation into the form  †,  where the dagger is the label of a hyperlink to its corresponding reference.

The contributor-to-reader transformation also equips the citation with a mouseover note that displays its reference. In the case of a subsidiary reference, the mouseover note also contains the title of the corresponding root reference.

The Reference Section

Need 23 notes a lack of structure in reference sections. A noticeable improvement is to collect all references with the same root identifier into a paragraph or subsection beginning with the root reference for that root identifier.

For the reader, references are automatically ordered as follows:

Root Reference Structure

Overall Design of the Reference Elements. Need 4 talks about the need for a well-reasoned ordering of the reference elements. Need 18 talks about the need for general principles. Need 20 states that readers have two primary needs, suggesting that reference elements be organized into two categories. The first category helps the reader decide whether the referenced content is of interest, and the second helps the reader determine whether the referenced content is credible.

A root contributor reference has five reference elements — seven counting the optional favicon and the root identifier.

Assessment of interest

Favicon. Optionally, an indicated icon that helps identify the page or website containing the cited work.

Root identifier. An identifier used to identify citations pointing to the reference.

Title element. A compound element consisting of the work's title and other title-related information

Links element. A list of hyperlinks

Assessment of  credibility

Contributor element. A list of key contributor names and associated credibility-related information

Publishing element. The organization or organizations that performed publishing activities for the referenced work

Date element. The date the work was published, updated, or posted

The five core elements of this design are comparable to the four elements of the APA style[APA, elements]. The most significant difference is the addition of links as a new core element.


APA Element
Title Title
Links Source
Contributors Authors
Publisher Source
Date Date

Punctuation. The ability to transform contributor references into reader references demands that references be machine parsable. Need 5 alludes to the fact that with existing guidance, getting the punctuation right may require careful study. Need 18 notes the desirability of simple general principles.

Each reference element ends with sentence-ending punctuation followed by white space. If a period, question mark, or exclamation point followed by white space is necessary inside a reference element, escape it with a backslash. For example, "Yo\! Yes\?" transforms to Chris Raschka's story, Yo! Yes?[yo-yes].

Abbreviations. Need 6 alludes to the fact that the use of abbreviations may be counterproductive in some cases.

There are no required abbreviations. This convention differs from the ink-and-paper world, where there is a need to conserve paper. As an example, the JoVE is better expressed as the Journal of Visualized Experiments.

Omitted Elements. The importance of the five core reference elements does not hinge on what contributors choose to share about their work. If the contributors of a referenced work omit any of the five main reference elements, the omission is as significant to the reader as its inclusion would have been. Here's why:

Titles. Any work worthy of mentioning is worthy of a short titular summary, even if the citing document must provide it.

URLs. If a work seriously has no presence on the Internet, the reader needs to know that looking for it could be a fool's errand.

Contributors. Any work that can be shared has somehow been generated. Simply omitting this information would compromise the overall structure of a reference and could potentially hide the fact that helpful information is being hidden from the reader.

Publishing. If a generated work can be known to both authors and readers, it has been conveyed somehow. Information on how that happened is an additional way for the reader to assess the credibility and perhaps find additional similar content. Outside of the dark web, this information is always visible to some extent.

Dates. Omitting the date is disastrous because the date is what allows readers to know if a referenced page has been rewritten after the citing document was written.

Reference Elements

Favicon. Need 24 notes that the visual appeal of traditional reference sections could stand improvement. The accompanying discussion states that some bibliographies address visual appeal by including graphical content. The favicon addresses the lack of visual content with the following guidance, guidance that is given more completely in the favicon section of the preliminary guidance document.

By default, the transformation algorithm gets a favicon from the reference's first linked web page. This default can be overridden by explicitly specifying the icon, like this: icon image-path. The algorithm then uses the provided image path.

Reference Identifier.

Reference identifiers are modeled directly after the citations. For example, the root citation \[twar] refers to the reference whose identifier is twar.

Title Element

Provide a preferred title, an optional alternative title, any needed title appendages, and optional title clarifications.

A reference can have more than one title. If the title is in a foreign language, there is both a foreign title and a translated title. For the sake of reader convenience, when there are two titles, the first title should be the one readers are more likely to appreciate. Typically, the second title is the document's original title. The second title is set off with parentheses.

A title appendage is anything needed to clarify which document the title refers to. For example, version, volume, issue, build, release, edition, supplement. The title appendage follows the title. It is set off by a comma or semicolon as appropriate.

A title clarification is set off with square brackets. Common clarifications include a "book review," "clinical trial," "consensus document," "exposition," "large-scale study," "literature review," and "news article."

The provider-to-reader transformation italicizes the titles of root references by default. An author who wishes to override the default can do so by making explicit use of italics. The use of italics in titles is essentially a matter of taste.

The title element can turn up in various places. Typically, it is on a web page's face. Often, it is in the page's HTML source, in the <title> element. These titles may be different, in which case the one on the document face is probably more recognizable. In the rare case where a page has no title, make up a titular description and wrap it in parentheses. Alternatively, use the first few words of the referenced document and enclose them in quotes.

Title examples

Consider the following title elements given in the author's view:

Yo\! Yes\? Multiple Editions[yo-yes]
Macbeth (The Tragedy of Macbeth)[macbeth]
Multiple Book URLs (Box 67 Multiple URLs)[NLM, URLs-books]
The Analects \[of Confucius] (论语)[secret]

 Yo! Yes? is a single illustrated story that has been presented in 21 editions. To see the 21 editions, follow the hyperlink.

The second and third titles show that the need for alternative titles isn't just due to language barriers. The Analects has been pre-italicized to keep the format transformation from italicizing the following Chinese title.

Here are three more examples:

After the Season \[in The Poem Tree anthology] † 
Badlands \[review of the film Badlands by Terrence Malick] † 
"'What's to-day, my fine fellow?' said Scrooge" † 

These titles illustrate the following:

a title clarified by reference to a containing anthology
a film review clarified by mention of the film reviewed
a quoted passage used as the title of a subsidiary reference

Time out for some terminology.

The links element provides a list of one or more links to representations of referenced content. The representations are of two kinds: direct links to directly available online content and connoting links to related information. A work that is not directly available may still have a linkable online presence. For example, there may be connecting links to an abstract or a review or there may be a link to an online vendor.

A link has the following structure:

<a href=URL #fragment id ...>label<a> \[clarification] .

The href attribute has two optional fields, a URL field and a fragment id field.:

The URL field specifies a file or similar entity. If the URL field is omitted, the link refers to the current file. The fragment id field, if present, is the id of a named element in the specified file. Depending on context, the fragment id may represent a point in the specified file or the region that, in the DOM tree, would have the named point as its root. This named point is the link's HTML target. The combination of the URL and the fragment id is known as a fragment URL

The visible, clickable portion of the link is its label. Clicking on the label amounts to following the link to its HTML target. The physical location of the link is its link source.

Finally, the natural-language clarification may refer to a point or region in the scope of the link's HTML target; this is the link's target. The scope of a point consists of all points below that point in the HTML parse tree. Clarifications are needed when describing a point that doesn't have an id, as such points cannot be HTML targets.

A link's clickable label is responsible for distinguishing between direct and connecting links. Labels for direct links include the terms "text," "full text, "image, "video", and "PDF." Labels for connecting links include "abstract," "comment," "commentary," "errata," "related text," "review," "condensed," "vendor," and so forth. Put direct links before connecting links.

Links for Directly Available Online Documents

Consider the Cherry Tree reference in Example 1. Its first link, image, goes directly to a digitized presentation of an engraving. In addition, this reference also has two connecting links, namely explanation and history.

A link to a linkable fragment in a containing online document uses a fragment URL. Consider the reference,

Classification \[of lung cancers]. Text. WikiProject Medicine. Wikipedia. Updated 2021 September 28\[lung-cancer].

The link's fragment URL is

Connecting Links for Documents that are not Directly Available

The links for a document that is not directly available describe offline presentations and online portrayals such as an available vendor, synopsis, or review. Consider the following example,

Midnight in the Garden of Good and Evil. Vendor, book review, synopsis. John Brandt (bio). Random House. Published 1994 January 13 † .

In this reference, vendor, book review, and synopsis are online connecting links.

Page Numbers. If a reference has no direct links, treat the page number as a clarification of the link ttle. If a reference has direct links and the page number(s) are offline, treat the page number(s) as clarifications of the direct link(s).

Here is a reference in which the page number is a clarification of the reference's direct link:

Title \[in Associated Press Style: Quick Reference Guide]. PDF \[ page 7].  Colorado Department of Health and Environment. Self-published. Undated.

Here is a reference where there is no direct link and the page number is treated as a title clarification:

9.4 Four Elements of a Reference \[page 283]. Tutorial † . ~. ~. ~.

Here is another example of a title clarification:

Caraway \[in The Encyclopedia of Essential Oils] pages 97-98. Kindle eBook. . Julia Lawless. Red Wheel. 2013 June 1.

Here is  a reference from Example 1, where the page range is a clarification of the reference's direct link:

Childhood Stories of George Washington. PDF \[pages 3-6]. Harriet G Reiter (storyteller), Katherine Follett (editor), Tad Butler (illustrator). Reading A-Z. 1906.

The link, PDF \[pages 3-6], includes a description of the root document, namely "PDF." Since the URL for the link points to the entire document rather than the specific portion being referenced, the page range is appended unlinked to the link's label. The page range is an example of a link clarification.

Here is another example of a link clarification:

"'What's to-day, my fine fellow?' said Scrooge". Text \[page 110] ~. ~. ~ † .

Link Quality. Try to choose URLs that qualify as permalinks.

To get the permalink for a Facebook post, click on the post's date. The permalink will appear in the browser's address bar.

To get the permalink for a Twitter tweet, click on the tweet. To get the permalink for an Instagram picture or video, click on that.

Convert a DOI (Document Object Identifier) to a permalink by prefixing "" to the DOI.

If a reference has no hyperlinks, use "Unlinked" for the Links element. The provider-to-reader transformation sets such references in a gray color.

Contributor Element. Need 7 suggests that the number of authors to list is related to the referenced work's likely audience. Need 21 addresses author credibility by introducing biographies and author pedigrees as welcome supplements to an author's institutional affiliation. Need 30 includes a detailed analysis of contributor roles, a subject that is only weakly addressed in existing guides. Need 18 regarding the need for simplicity motivates giving a uniform treatment to authors and other contributors.

The discussion regarding Need 10 notes the need for specifying the recipient of a personal communication and mentions that Zotero treats recipients as secondary "item creators."[zotero, recipient]

Putting these thoughts together, we have the following guidance, guidance that is given more completely in the Contributor Element section of the preliminary guidance document.

List key contributors with authors and other content creators first. A contributor's name may include honorific titles or pedigrees, for example, LCSW, MD. A contributor can be an individual, a group, or an organization.

The number of contributors to list depends on the likely audience for the citing document. For example, if the likely audience consists mainly of authors of the referenced works, list as many authors as possible. If not every key contributor is listed, end the contributor list with "and others" or "et al."

If no person or organization acknowledges responsibility for creating the work's content, use "unattributed" for the contributor element.  If the publisher is the same as the contributor, use "self-published" for the publisher element.

Each contributor is optionally followed by a parenthesized list of contributor attributes such as a contributor's role or roles, organizational affiliations, or a bio. Give enough role information to distinguish authors from other contributors. An included bio, history, or about page can be given via a hyperlink.

The recipient of a personal communication may be treated as a secondary contributor.

Publishing Element. Need 11 asks what constitutes publishing and concludes that newspapers, journals, websites, publishers, and their imprints all may engage in acts of publishing. Following tradition, we use the name of a publication as a stand-in for the names of its editors.

Need 12 suggests that, in the case of multiple publishers, the preferred publisher to list first is the one that is most credible. And because of the way we constructed the link element, that would be the publisher of the first representation. We have the following guidance, guidance that is given more completely in the Publishing Element section of the preliminary guidance document.

Give the organization or organizations involved in publishing activities such as review, acceptance, final editing, marketing, and distribution to an intended audience. Likely examples include traditional publishers or their independently operating imprints, newspapers, journals, and websites. In each case, the title of the publishing entity suffices. If the work was published before 1900, include the publisher's city. In many cases, the cited content is contemporaneous with the web page on which it appears, and the likely publisher is the page's website.

If there are several publishers, use the publishers of the first link in the link element or use "multiple publishers" for the publishing element. If a work has been placed online without significant publishing activities or if no publisher can be found, list the title of the hosting website as the publishing element. The website's title is the title of its home page.

Date Element. Need 14 provides four reasons as to why a date of access is never appropriate. Need 13 indicates that the date of interest to the reader is probably the date of the referenced content rather than the date of the page itself. Need 11 points out that online platforms such as X (Twitter) and Facebook do not really publish posts and tweets. Need 19 warns against requirements that lack a strong justification, as for example, specific date formats.

These insights lead to the following guidance, guidance that is given more completely in the Date Element section of the preliminary guidance document.

Say how and when the content has been created or placed online. Regarding how, there are several possibilities:

Posted: Posted without significant publishing activities.

Published: Established as part of a publishing process.

Updated: Modified and reposted.

It is acceptable to use more than one of the above choices. For example, a document may have been posted online before being officially published. In the event that content has both online and offline publication dates, the earlier date is more appropriate.

In addition to the above, there are several dates that are not included in a reference because they are not properties of the cited content: a document review date, dates of comments on the cited content, the date on which a content creator last accessed the cited content, the date on which a website posted the content. In the case of books, the copyright date is a plausible though inaccurate guess as to the date of publication.

The format of the date element is up to the authors of the citing document.

Subsidiary References

Subsidiary references are like root references but with a few key differences.

A subsidiary reference omits the favicon.

The first element of a subsidiary reference consists of a root identifier and a part name. The part name is a brief indication of the subsidiary work's title.

Because a subsidiary reference will become part of a segment that begins with the corresponding root reference, there is no reason for a subsidiary reference to include redundant information from its root reference. Replace redundant elements with tildes.

5. Transformation Algorithm

Good practice in software development involves the identification of design requirements, provision of worked examples, a proposed design, a reference implementation, and documentation.

Design Requirements

The algorithm must translate contributor citations and references to reader citations and references. The transformation must perform in real-time, which is to say that when a document created in the contributor format moves from an editor to a browser, it automatically opens in the format designed for readers.

The transformation algorithm resolves several esthetic Questions:

A technical note: The daggers are padded with hair spaces to improve mouse-ability: " † " as opposed to "".

A Worked Example

The following example is given in the contributor format. Click on the blue button to see the corresponding reader style.


Katalin Karikó devoted forty years to developing the mRNA vaccine technology[Karikó]. Yet, she remains relatively unknown[wealth]. Doctor Anthony Fauci has led the public fight against infectious diseases for forty years[niaid]. His accolades include the well-publicized threat of a public beheading[beheading].


Karikó. Katalin Karikó’s research led to COVID-19 vaccines. Text. @ambasciatausa. U.S\. Embassy Consulate in Italy. Updated 2021 March 9.

wealth. This scientist’s decades of mRNA research led to both COVID-19 vaccines. Text. Dana Kennedy (bio). The New York Post. Updated 2020 December 5.

beheading. Twitter bans Steve Bannon for video suggesting violence against Fauci, FBI Director Wray. Text. Jaclyn Peiser (about). Seattle Times. Updated 2020 November 6.

niaid. Anthony S\. Fauci, M.D., NIAID Director. Text. No author. National Institute of Allergies and Infectious Diseases. No date.

Example 1. A Worked Example

As this example illustrates, it is possible for a document to have multiple reference sections. None of the references in this example are found in this paper's main reference section.

Algorithm Design

The transformation that translates contributor forms into corresponding reader forms does the following:

The handling of inconsistencies is accomplished as follows:

Using the Reference Implementation

A typical document structure is depicted below. The References heading separates the main text from the reference section and also shows where these entities fit into the overall document structure. The actively processed portion is at the same level as the References heading, which may be tagged with any of the tags H1 through H6. There can be other headings and unprocessed material following the references.

<div ...>
... main text ...
<h*>References</h*> ...
... references ...
<h*>following heading</h*>...

Copy the following into the header:

<script type='text/JavaScript'

<link rel="stylesheet" type="text/css" href="styles/providerToReader.css">

Key Features

There are several crucial differences between traditional style guides and the citation architecture growing out of this research.

The document Tomorrow's Citations: Preliminary Guide for Content Creators refines the guidance developed here and provides information on finding the various reference elements in a web page.


WWW. The World Wide Web. Text. editors. Updated 2019 October 28.

macbeth. Macbeth (The Tragedy of Macbeth). Text [playscript]. William Shakespeare (bio), Kenneth Muir (editor). Globe Theatre, London, Arden Shakespeare. Performed 1606, second Arden series published 1997 January 31.

IEEE. How to Cite References: IEEE Documentation Style. PDF examples. Unattributed. IEEE DataPort. Undated.

NLM. Citing Medicine, 2nd edition: the NLM style guide for authors, editors, and publishers. Full text [open-access book. Karen Patrias, Dan Wendling (technical editor). National Library of Medicine (US). Published 2007, updated 2020 August 5.

NLM, intro. Introduction. Text [Reference Lists Versus In-Text References]. ~. ~. Updated 2016 April 18.

NLM, article-type-journal. Article Type for Journal Articles on the Internet (optional). Text [chapter section]. ~. ~. Updated 2018 May 18.

NLM, content-type-book. Content Type for Entire Books on the Internet (optional). Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, content-type-bibliography. Content Type for Bibliographies (optional). Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, article-part. Citation Rules with Examples for Parts of Journal Articles. Text  [chapter section]. ~. ~. Updated 2018 May 18.

NLM, listservs. Citation Rules with Examples for Listservs and Similar Discussion Lists. Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, affiliation-books. Author Affiliation for Entire Books. Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, affiliation-articles. Author Affiliation for Journal Articles on the Internet. Text  [chapter section]. ~. ~. Updated 2018 May 18.

NLM, affiliation-web-pages. Citation Rules with Examples for Parts of Web Sites. Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, authors-article. Author for Journal Articles on the Internet. Text [chapter section]. ~. ~. Updated 2018 May 18 .

NLM, contributors. Editor and other Secondary Authors for Entire Books. Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, date-augmentation. Supplement/Part/Special Number to a Date for Journal Articles. Text  [chapter section]. ~. ~. Updated 2018 May 18.

NLM, volume-augmentation. Supplement/Part/Special Number to a Volume for Journal Articles. Text  [chapter section]. ~. ~. Updated 2018 May 18.

NLM, issue-augmentation. Supplement/Part/Special Number to an Issue for Journal Articles. Text  [chapter section]. ~. ~. Updated 2018 May 18.

NLM, book-edition. Edition for Entire Books. Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, URLs-books. Multiple Book URLs (Box 67 Multiple URLs). Text  [breakout]. ~. ~. Updated 2015 August 11.

NLM, URLs-journals. Multiple Journal URLs (Box 59 Multiple URLs). Text [breakout]. ~. ~. Updated 2018 May 18,

NLM, URLs-databases. Multiple Database URLs (Box 62 Multiple URLs). Text [breakout]. ~. ~. Updated 2018 May 18,

NLM, newspaper. Citation Rules with Examples for Newspaper Articles. Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, notes-reports. Citation Rules with Examples for Entire Reports. Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, accessed-date. Date of Citation for Homepages (required). Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, notes-books. Notes for Entire Books (optional). Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, website-publisher.  Sample Citation and Introduction to Citing Homepages. Text  [chapter section]. ~. ~. Updated 2015 August 11.

NLM, email. Citation Rules with Examples for Electronic Mail. Text  [chapter section]. ~. ~. Updated 2015 August 11.

icon icons/GitHub.png. pubreader. NLM/NCBI PubReader. Full text [GitHub repository]. Chris Maloney. National Center for Biotechnology Information. 2018 June 21.

secret. The Analects [of Confucius] (论语). [Chinese and English] text. Disciples of Confucius, James Legge (translator). Chinese Text Project. Written 475–221 BC, translated 1861.

wiki-tooltip. Reference Tooltips. Text [project description]. Yair rand, Jack who built the house. MediaWiki. 2021 April 7.

wiki-preview. Reference Previews. Text [project description]. Technical Wishes Project. Wikimedia. 2021 August 19.

wiki-overlay. Mobile design/Reference reveal. Text [project description]. Unattributed. MediaWiki. 2020 January 11.

APA. Publication Manual of the American Psychological Association, 7th edition. eBook vendors. American Psychological Association. Self-published. Published 2019 October 1, copyright 2020.

APA, authors. 9.8 Format of the Author Element [page 286]. Related APA blog. ~. ~. ~.

APA, punctuation. 9.5 Punctuation Within Reference List Entries [page 283. Related guidance. ~. ~. ~.

APA, personal. 8.9 Personal Communications [page 259]. Similar APA text. ~. ~. ~.

APA, citation. 8.10 Author–Date Citation System [page 261]. APA article. ~. ~. ~.

APA, roles. 9.10 Identification of Specialized Roles [page 287]. Related guidance. ~. ~. ~.

APA, retrieval-date. 9.16 Retrieval Date \[page 290]. Related guidance. ~. ~. ~.

APA, elements. 9.4 Four Elements of a Reference [page 283]. APA article. ~. ~. ~.

APA, web-page-reference. Web Page on a Website References. APA examples. Unattributed. American Psychological Association. Published 2020.

APA, edition. 9.19 Format of the Title Element [page 291. APA article section. ~. ~. ~.

icon icons/mla.png. MLA. MLA Handbook 9th. Kindle eBook. The Modern Language Association of America. Self-published. Published 2021 April 22.

MLA, authors. 5.8 Three or more authors [page 168]. Related guidance. ~. ~. ~.

MLA, author-roles. 5.44 Labels describing the contributor's role [pages 216-217]. Related guidance. ~. ~. ~.

MLA, parts. 5.101 Works in One Container [page 278]. Related work. ~. ~. ~.

MLA, version. 5.50 Version: How to Style [page 225]. Related guidance. ~. ~. ~.

MLA, 1900. 5.67 City of publication [/MLA8/version]. Related guidance. ~. ~. ~.

MLA, containers. 5.31 Title of Container: What it is [page 195]. Related guidance. ~. ~. ~.

MLA, figure-5.29. Examples of containers (figure 5.29) [page 196]. Related infographic. ~. ~. ~.

MLA, citation-guide. 6\. Citing Sources in the Text [page 314]. parent link. ~. ~. ~.

comes. The Chicago Manual of Style Online. Text [Online book]. Multiple authors (history). University of Chicago Press. Published 2017 September 5.

comes, author-date. 15.5: The author-date system — overview. Text, related guidance. ~. ~. ~.

comes, chapter. 14.106: Chapter in a single-author book. Text. ~. ~. ~.

comes, note-bibliography. 14.19: Notes and bibliography — an overview. Text, related guidance. ~. ~. ~.

comes, authors. 14.76: Two or more authors (or editors). Text, related guidance. ~. ~. ~.

comes, contributors. 14.105: Other contributors listed on the title page. Text, related guidance. ~. ~. ~.

comes, online-formats. 14.159: Books requiring a specific application or device (e-books). Text, related guide. ~. ~. ~.

comes, personal. 14.214: Personal communications. Text. ~. ~. ~.

comes, websites. 8.191: Titles of websites and web pages. Text, related guide. ~. ~. ~.

comes, citing-websites. 14.207: Citing web pages and websites. Text, related guide. ~. ~. ~.

comes, publisher. 14.133: Preferred form of publisher’s name. Text. ~. ~. ~.

zotero. Zotero | Your personal research assistant. Website. Corporation for Digital Scholarship. Self-published. Undated.

zotero, data-design. Item Types and Fields. Web page. ~. ~. ~.

zotero, recipient. Zotero Recipient. Text [recipient]. ~. ~. ~.

zotero, item-creators. Item Creators. [Text]. ~. ~. ~.

zotero, styles. Style Repository. Text [list]. ~. ~. ~.

cr, CRediT1. 14 Contributor Roles (Contributor Roles Defined, CRediT author statement). Text, [alternate] text, [alternate] text. Unattributed.,, Elsevier. Undated.

Herring. Use of Electronic Resources in Scholarly Electronic Journals: A Citation Analysis. Text. Susan Davis Herring. College & Research Libraries. 2002 July.

schema. Welcome to Text [website]. Multiple corporate authors. Updated 2021 July 7.

schema, role. Role: A Type. Text [Web page]. ~. ~. ~.

schema, honorific-suffix. honorificSuffix: A Property. Text [web page]. ~. ~. ~.

IOPScience. Author roles and responsibilities default. Text [opinion]. Unattributed. IOP Science. Undated.

ICMJE. Defining the Role of Authors and Contributors. Text [opinion]. Unattributed. International Committee of Medical Journal Editors. Undated.

patents. Patent basics. Text [exposition]. Unattributed. United States Patent and Trademark Office. Updated 2021 July 1.

Childers. Different Roles in Comic Books. Text [resource]. Matthew Childers (author, illustrator, writer, bio). Updated 2020 November 4.

credibility1. How Do People Evaluate a Web Site’s Credibility? Text [large-scale study]. B J Fogg, PhD (bio), Cathy Soohoo, David Danielson, et al. Updated 2002 November 11.

credibility2. How do users evaluate the credibility of Web sites? Abstract. B J Fogg, PhD (bio), Cathy Soohoo, David Danielson, et al. Association for Computing Machinery. Published 2003 June.

galov. A Dive Into the Ocean of Web Design Statistics. Text [literature survey]. Nick Galov (bio). Hosting Tribunal. Updated 2021 January 20.

jeff-letter. Thomas Jefferson to James Madison. Image. Thomas Jefferson (bio), James Madison (Addressee). Library of Congress. Written 1803 March 22.

brave. The Brave. Synopsis, book review. Nicholas Evans (bio). The Good Book Company. Published 2010 January 1.

yo-yes. Yo\! Yes?, multiple editions. Boardbook, hardcover, review. Chris Raschka (author, illustrator, bio). Multiple publishers. Published 1993 March 1 through 2020 April 21.

einstein. On the electrodynamics of moving bodies (Zur Elektrodynamik bewegter Körper[German]). English translation. Albert Einstein (bio). Annalen der Physik. 1905.

putnam. G P Putnam's Sons. Imprint description. Unattributed. Penguin. Undated.

icon icons/globeIcon.png. color-TV. The History of Television (or, How Did This Get So Big?). Text [course materials]. Phoebe Sengers (bio). Cornell University. Undated.

color-news. The Trend Toward Color: Some Newspapers Want to Stay Just Plain Read. Text. David Shaw. Los Angeles Times. Published 1986 March 14.

favicon. How We Got the Favicon. Text [historical essay]. Jay Hoffmann. History of the Web. Published 2017 July 24.

wikipedia. Wikipedia: The Free Encyclopedia. Text. Multiple authors. Wikimedia Foundation. Updated continuously.

ie5. Internet Explorer 5. Text. WikiProjects Computing / Software, Microsoft, et al. Wikipedia. Updated 2021 October 11.

DOI-article. Factsheet: DOI® Resolution Documentation. Text. Unattributed. Updated 2020 July 4.

icon icons/dickens.png. dickens. A Christmas Carol. Full  text. Charles Dickens(bio), Arthur C Michael (illustrator). Hodder and Stoughton, Library of Congress. Published 1911, posted 2019 December 23.