citation

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Loosely, a citation is a reference to a published or unpublished source (not always the original source). More precisely, a citation is an abbreviated alphanumeric expression (e.g. [Newell84]) embedded in the body of a intellectual work that denotes an entry in the bibliographic references section of the work for the purpose of acknowledging the relevance of the works of others to the topic of discussion at the spot where the citation appears. Generally the combination of both the in-body citation and the bibliographic entry constitutes what is commonly thought of as a citation (whereas bibliographic entries by themselves are not).

A prime purpose of a citation is intellectual honesty; to attribute to other authors the ideas they have previously expressed, rather than give the appearance to the work's readers that the work's authors are the original wellsprings of those ideas.

The forms of citations generally subscribe to one of the generally-accepted citations systems, such as the Harvard, APA, and other citations systems, as their syntactic conventions are widely-known and easily interpreted by readers. Each of these citation systems has its respective advantages and disadvantages relative to the tradeoffs of being informative (but not too disruptive) and thus should be chosen relative to the needs of the type of publication being crafted. Editors will often specify the citation system to use.

Bibliographies, and other list-like compilations of references, are generally not considered citations because they do not fulfill the true spirit of the term: deliberate acknowledgement by other authors of the priority of one's ideas.

Some terms

A bibliographic citation is a reference to a book, article, web page, or other published item. Citations should supply sufficient detail to identify the item uniquely.^[1] Different citation systems and styles are used in scientific citation, legal citation, prior art, and the arts and the humanities.

A citation number, used in some citation systems, is a number or symbol added inline and usually in superscript, to refer readers to a footnote or endnote that cites the source. In other citation systems, an inline parenthetical reference is used rather than a citation number, with limited information such as the author's last name, year of publication, and page number referenced; a full identification of the source will then appear in an appended bibliography.

Citation content

Citation content can vary depending on the type of source and may include:

• Book: author(s), book title, publisher, date of publication, and page number(s) if appropriate.^[2][3]
• Journal: article title, journal title, date of publication, and page number(s).
• Newspaper: author(s), article title, name of newspaper, section title and page number(s) if desired, date of publication.
• Web site: author(s), article and publication title where appropriate, as well as a URL, and a date when the site was accessed.
• Play: inline citations offer part, scene, and line numbers, the latter separated by periods: 4.452 refers to scene 4, line 452. For example, "In Eugene Onegin, Onegin rejects Tanya when she is free to be his, and only decides he wants her when she is already married" (Pushkin 4.452-53).^[4]
• Poem: spaced slashes are normally used to indicate separate lines of a poem, and parenthetical citations usually include the line number(s). For example: "For I must love because I live / And life in me is what you give." (Brennan, lines 15–16).^[4]

Unique identifiers

Along with information such as author(s), date of publication, title and page numbers, citations may also include unique identifiers depending on the type of work being referred to.

• Citations of books may include an International Standard Book Number (ISBN).
• Specific volumes, articles or other identifiable parts of a periodical, may have an associated Serial Item and Contribution Identifier (SICI).
• Electronic documents may have a digital object identifier (DOI).
• Biomedical research articles may have a PubMed Identifier (PMID).

Citation systems

Broadly speaking, there are two citation systems:^[5][6][7]

Note systems

Note systems involve the use of sequential numbers in the text which refer to either footnotes (notes at the end of the page) or endnotes (a note on a separate page at the end of the paper) which gives the source detail. The notes system may or may not require a full bibliography, depending on whether the writer has used a full note form or a shortened note form.

For example, an excerpt from the text of a paper using a notes system without a full bibliography could look like this:

"The five stages of grief are denial, anger, bargaining, depression, and acceptance."¹

The note, located either at the foot of the page (footnote) or at the end of the paper (endnote) would look like this:

1. Elisabeth Kübler-Ross, On Death and Dying (New York: Macmillan, 1969) 45–60.

In a paper which contains a full bibliography, the shortened note could look like this:

1. Kübler-Ross, On Death and Dying 45–60.

and the bibliography entry, which would be required with a shortened note, would look like this:

Kübler-Ross, Elisabeth. On Death and Dying. New York: Macmillan, 1969.

Citation styles

Citation styles can be broadly divided into styles common to the Humanities and the Sciences, though there is considerable overlap. Some style guides, such as the Chicago Manual of Style, are quite flexible and cover both parenthetical and note citation systems.^[7] Others, such as MLA and APA styles, specify formats within the context of a single citation system.^[6] These may be referred to as citation formats as well as citation styles.^[8][9][10] The various guides thus specify order of appearance, for example, of publication date, title, and page numbers following the author name, in addition to conventions of punctuation, use of italics, emphasis, parenthesis, quotation marks, etc, particular to their style.

A number of organizations have created styles to fit their needs, consequently a number of different guides exist. Individual publishers often have their own in-house variations as well, and some works are so long established as to have their own citation methods too: Stephanus pagination for Plato; Bekker numbers for Aristotle; citing the Bible by book, chapter and verse; or Shakespeare notation by play, act and scene.

Some examples of style guides include:

Humanities

• The American Political Science Association (APSA) relies on the Style Manual for Political Science, a style often used by political science scholars and historians. It is largely based on that of the Chicago Manual of Style.
• The ASA style of American Sociological Association is one of the main styles used in sociological publications.
• The Chicago Style (CMOS) was developed and its guide is The Chicago Manual of Style. Some social sciences and humanities scholars use the nearly identical Turabian style. Used by writers in many fields.
• The Columbia Style was made by Janice R. Walker and Todd Taylor to give detailed guidelines for citing internet sources. Columbia Style offers models for both the humanities and the sciences.
• Evidence Explained: Citing History Sources from Artifacts to Cyberspace by Elizabeth Shown Mills covers primary sources not included in CMOS, such as censuses, court, land, government, business, and church records. Includes sources in electronic format. Used by genealogists and historians.
• Harvard referencing (or author-date system) is a specific kind of parenthetical referencing. Parenthetical referencing is recommended by both the British Standards Institution and the Modern Language Association. Harvard referencing involves a short author-date reference, e.g., "(Smith, 2000)", being inserted after the cited text within parentheses and the full reference to the source being listed at the end of the article.
• MLA style was developed by the Modern Language Association and is most often used in the arts and the humanities, particularly in English studies, other literary studies, including comparative literature and literary criticism in languages other than English ("foreign languages"), and some interdisciplinary studies, such as cultural studies, drama and theatre, film, and other media, including television. This style of citations and bibliographical format uses parenthetical referencing with author-page (Smith 395) or author-[short] title-page (Smith, Contingencies 42) in the case of more than one work by the same author within parenttheses in the text, keyed to an alphabetical list of sources on a "Works Cited" page at the end of the paper, as well as notes (footnotes or endnotes). See The MLA Style Manual and The MLA Handbook for Writers of Research Papers, particularly Citation and bibliography format.^[11]
• The MHRA Style Guide is published by the Modern Humanities Research Association (MHRA) and most widely used in the arts and humanities in the United Kingdom, where the MHRA is based. It is available for sale both in the UK and in the United States. It is similar to MLA style, but has some differences. For example, MHRA style uses footnotes that reference a citation fully while also providing a bibliography. Some readers find it advantageous that the footnotes provide full citations, instead of shortened references, so that they do not need to consult the bibliography while reading for the rest of the publication details.^[12]

Legal

• The Bluebook is a citation system traditionally used in American academic legal writing, and the Bluebook (or similar systems derived from it) are used by many courts.^[13] At present, academic legal articles are always footnoted, but motions submitted to courts and court opinions traditionally use inline citations which are either separate sentences or separate clauses.
• The legal citation style used almost universally in Canada is based on the Canadian Guide to Uniform Legal Citation (aka McGill Guide), published by McGill Law Journal.^[14]

Sciences, mathematics, electrical engineering, physiology, and medicine

• The American Chemical Society style, or ACS style, is often used in chemistry and other physical sciences. In ACS style references are numbered in the text and in the reference list, and numbers are repeated throughout the text as needed.
• In the style of the American Institute of Physics (AIP style), references are also numbered in the text and in the reference list, with numbers repeated throughout the text as needed.
• Styles developed for the American Mathematical Society (AMS), or AMS styles, such as AMS-LaTeX, are typically implemented using the BibTeX tool in the LaTeX typesetting environment. Brackets with author’s initials and year are inserted in the text and at the beginning of the reference. Typical citations are listed in-line with alphabetic-label format, e.g. [AB90]. This type of style is also called a "Authorship trigraph."
• The Vancouver system, recommended by the Council of Science Editors (CSE), is used in medical and scientific papers and research.
  • In one major variant, that used by the American Society of Mechanical Engineers (AME), citation numbers are included in the text in square brackets rather than as superscripts. All bibliographical information is exclusively included in the list of references at the end of the document, next to the respective citation number.
  • The International Committee of Medical Journal Editors (ICMJE) is reportedly the original kernel of this biomedical style which evolved from the Vancouver 1978 editors' meeting.^[15] The MEDLINE/PubMed database uses this citation style and the National Library of Medicine provides "ICMJE Uniform Requirements for Manuscripts Submitted to Biomedical Journals -- Sample References".^[16]
• The style of the Institute of Electrical and Electronics Engineers (IEEE), or IEEE style, encloses citation numbers within square brackets and arranges the reference list by the order of citation, not by alphabetical order.
• Pechenik Citation Style is a style described in A Short Guide to Writing about Biology, 6th ed. (2007), by Jan A. Pechenik.^[17]
• In 2006, Eugene Garfield proposed a bibliographic system for scientific literature, to consolidate the integrity of scientific publications.^[18]

Social sciences

• The style of the American Psychological Association, or APA style, published in The Style Manual of the APA, is most often used in social sciences. APA style uses Harvard referencing within the text, listing the author's name and year of publication, keyed to an alphabetical list of sources at the end of the paper on a References page.
• The American Political Science Association publishes both a style manual and a style guide for publications in this field.^[19]

See also

• Acknowledgment (creative arts)
• Bible citation
• Case citation
• Citation creator
• Citation signal
• Citationality
• Credit (creative arts)
• Cross-reference
• Scholarly method
• Source evaluation
• Style guide

Notes

References

Further reading

Guidelines

• Citing Government Documents/Government Agency Style Manuals, University of North Texas Libraries.
• Document it Citation and Referee AMS, and the AMSRefs package.
• Guide to Citation Style Guides
• ONLINE! Citation Styles (An online guide to different citation formats)
• "What is citation?", Turnitin.com

Examples

• Illustrated examples, generated using BibTeX, of several major styles, including more than those listed above.
• PDF file bibstyles.pdf illustrates how several bibliographic styles appear with citations and reference entries, generated using BibTeX.

Style guides

• AMA Citation Style
• How to write footnotes, endnotes and electronic references in a proper format
• Swarthmore library's Guide to Citation Styles for Science and Humanities.

Tools

• Citation Machine for MLA, APA, Chicago, and Turabian formats

Other online resources

• CiteTerm An online resource for cited terms.
• thehistorysite.org Online resources for historical research and writing.