There are three primary styles of source citations:
The purpose of all three styles is to acknowledge the sources that have been used, and to enable readers to find those sources.
Academic disciplines differ in:
These differences between disciplines are reflected in the choice of citation style.
The social sciences put an emphasis on easily seeing the date of a cited article, hence the date is the second element of an entry in an APA works cited list, and the date is also included in the parenthetical citation within the text.
In humanities scholarship, which uses the MLA style, it is important to clearly identify which portion of an outside source is being discussed. Therefore the MLA in-text parenthetical citation includes the page number of the cited source, and the date is one of the later elements in the works cited citation.
Historians frequently refer to multiple sources in their research, and hence use the Chicago Style notes and bibliography system, with its footnotes (or endnotes), to avoid interrupting the flow of their texts with multiple parenthetical references.
Note Citation for a Book:
The numbered note below would correspond to a superscript reference number in the body of the research paper text. In the example below, the note provides the complete citation.
If a source is cited more than once, then an shortened form of the note may used after the initial long form note:
3. Hohn, Moby-Duck, xx-xx.
Corresponding Bibliography Entry for the Book:
Note Citation for an Article from an Online Database:
Subsequent references to the same source may use a shortened form of the note:
3. Derraik, "Pollution of the Marine Environment," xx-xx.
Corresponding Bibliography Entry for an Online Journal Article: