In the Name-Year system, citations are provided in the main text through parenthetical citations.
Rule: Citations precede the final punctuation of the sentence that contains the reference. The basic elements of the in-text citation are the author's last name and the year of publication of the work. A space separates the name and the year.
The discussion of this phenomenon still influences scientists today (Einstein 1931).
Rule: If the last name of the author or authors appears in the sentence, only the year of publication need be included in parentheses.
Einstein provides a lengthy description of this phenomenon (1931).
Rule: If a work has two authors, provide the names of both authors separated by the word "and."
Evidence of this phenomenon has been demonstrated in agrarian regions in India (Singh and Sharma 2004).
Rule: If a work has three or more authors, provide the names of the first author followed by "et al."
Logic systems displaying this behavior have been shown to allow abductive reasoning (Reyes-Cabello et al. 2005).
Rule: If your paper cites two works from the same year with authors who have the same last name, distinguish between the authors by providing the authors' initials in the citation. Note that no commas or periods are used, and that the initials are not separated by a space.
(Wiles NM 2007)
(Wiles KB 2007)
Rule: If your paper cites two or more works from the same author in the same year, distinguish the works by appending a lowercase letter to the year in your citation. The paper published earliest in the year should be labeled "a," the next "b," etc. The publication dates for the citations in the works-cited page should be modified in the same way.
Rule: If a work has a corporation or government body as an author, use the initials of the organization's name to create a shortened form of the name. If the organization's name has a familiar abbreviated form, that form may be used as the shortened version. In your works-cited page, precede the matching citation with the initialism used to refer to that organization, enclosed in square brackets.
[IOM] Institute of Medicine (US). 1975. Legalized abortion and the public health: report of a study by a committee of the Institute of Medicine. Washington (DC): National Academy of Sciences.
Rule: If a work does not have an identifiable author, use the work in an in-text citation by using the first word or first few words of the title, followed by an ellipsis, in place of the author's name. Use only as many words as are necessary to distinguish the cited work from other works you refer to.
Rule: If a work does not have an identifiable publication date, use a copyright date. Copyright dates are immediately preceded by the letter "c" to indicate their nature. If neither publication nor copyright date is available, use the date of last modification, revision, or update, enclosed in square brackets and preceded by the expression "mod," "rev", or "updated," as appropriate, and a space. If no date is available, use "[date unknown]" in place of the date. In each of these cases, the same notation should be used when expressing the date of the cited work on the works-cited page.
(Morris [mod 1999])
(Lederer [date unknown])
Rule: In the Name-Year system it is permissible to refer to multiple works in the same citation. For multiple works by different authors, order the references chronologically and separate them using semicolons, within a single set of parentheses. For multiple citations from the same author, include the name only once and list the years of publication chronologically, separated by commas.
Multiple works by different authors:
(Mulder 1997; Scully 1999; Skinner 2000)
Multiple works by the same author:
(Krycek 1996, 1999)