Parenthetical documentation is a citation in the body of your paper that identifies for the reader the source of the reference you have made or the quotation you have used.
The source of your reference or quotation is provided with a full citation in the "Works Cited" portion of your paper.
Each reference should point unambiguously to a single entry in the References list. This is normally done with the author's surname and date of publication, which may appear in the text or in the parenthetical reference.
If the source you are citing has two authors, both must be cited in the in-text reference.
Example: This type of approach has been legitimately criticized (Levine & Shefner, 1991).
Three to Five Authors
When the source has three to five authors, cite all of them the first time the reference is made. In later references, shorten this to the first author's name followed by "et al."
Example: (Sokolov et al., 2013)
Six or More Authors
When the source has six or more authors, shorten this to the first author's name followed by "et al." in all cases.
Example: (Matuskey et al., 2012)
A parenthetical citation can refer to multiple sources, if appropriate. Separate them with a semicolon.
Example: (Oranje & Glenthøj, 2013; Xiang et al., 2013).
For more details on in-text references, see Publication manual, 6.11-6.21, pp. 174-179.