Citations

A citation is a credit or reference to another document or source which documents both influence and authority. There are many rules for the format and use of such citations in different fields:

Varying rules and practices for citations apply in a science, a law, a theological citing of authority (e.g. the isnad which "back" the hadith in Islam), the prior art that applies in patent law, or marks applied in copyright.

Definitions of plagiarism, uniqueness or innovation, trustworthiness or reliability vary so widely among these fields that the use of citations has no simple common practice. In any of these fields the concept of a citation index can apply, which summarizes published citations of a given publication.

When using citations, one generally uses both a works cited page or section--also called the bibliography, source list or list of references--in conjunction with parenthetical citations (citations which refer the reader to a particular cited work). As an alternative to parenthetical citations, some styles include citations in footnotes, which appear at the end of each page, or endnotes, which appear at the end of the document.

Citation styles
Some works are so long established as to have their own citation methods: Stephanus pagination for Plato; Bekker numbers for Aristotle; line numbers in poems; bible citation by book, chapter and verse; or Shakespeare notation by play, act and scene.

Various organizations have created systems of citation to fit their needs. Some of the most important are:


 * The ACS style is the American Chemical Society style format and is often used in chemical literature.


 * The APA style is the American Psychological Association style format which is most often used in social sciences. APA style lists sources at the end of the paper, on a References Page.  Listing electronic sources of information is more detailed in APA style than in MLA style.  APA style uses parenthetical citation within the text, listing the author's name, the year the work was made, and the page that the information may be found on.  These work much like the MLA style's parenthetical citations.


 * The American Political Science Association (APSA) publication on citation is the Style Manual for Political Science, which is a system often used by political science scholars and historians. It is largely based on that of the Chicago Manual of Style.


 * The Bluebook is the citation system traditionally used in American academic legal writing, and the Bluebook (or similar systems derived from it) are used by many courts. The dominance of the Bluebook is currently being challenged by the newer ALWD Citation Manual. 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. Inline citation is controversial among lawyers, because it is thought to be one of the reasons why most laypersons find legal writing hard to read.


 * The CBE style is the Council of Biology Editors style format, which is most often used in scientific papers and research.


 * The Chicago Style was developed and its guide is The Chicago Manual of Style. Some social sciences and humanities scholars use the nearly identical Turabian style.


 * 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.  More information can be found in The Columbia Guide to Online Style.


 * The MHRA Style Guide is the Modern Humanities Research Association style format and is most often used in the arts and humanities, particularly in the United Kingdom where the MHRA is based. It is fairly similar to the MLA style, but with some differences. The style guide uses footnotes that fully reference a citation and has a bibliography at the end. Its major advantage is that a reader does not need to consult the bibliography to find a reference as the footnote provides all the details. The guide is available for free download.


 * MLA style was developed by The Modern Language Association and is most often used in English studies, comparative literature, foreign-language literary criticism, and some other fields in the humanities. MLA style uses a Works Cited Page to list works at the end of the paper.  Brief parenthetical citations, which include an author and page (if applicable), are used within the text.  These direct readers to the work of the author on the list of works cited, and the page of the work where the information is located (e.g. (Smith 107) refers the reader to page 107 of the work made by someone named Smith).  More information can be found in the MLA Handbook for Writers of Research Papers.

Citations permit readers to put the claims to a better test by consulting the earlier work. Authors often engage earlier work directly, explaining why they agree or differ from earlier views. Ideally, sources are primary (first-hand), recent, with good ethos, credentials, and citations. Some have questioned the authority assumed or conferred by citation, considering it endlessly recursive, the authority of a work resting on its citations, the authority of which in turn rely on their citations.