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 Works Cited list. This is normally done with the author's surname, which may appear in the text or in the parenthetical reference.
The location of the referenced material in the source should be identified specifically, typically with the page number.
Specifics:
If the source you are citing has multiple authors, all must be cited in the parenthetical reference.
Example: This type of approach has been legitimately criticized (Kenney and Rice, 905).
If your Works Cited includes multiple sources by the same author(s), you must include a shortened title in the parenthetical reference.
Example: This sort of variable can be accounted for in the analysis (Ohanian, "Macroeconomic Effects" 28)
A parenthetical citation can refer to multiple sources, if appropriate.
Example: Others have made this observation (e.g., Thiessen 25; Bowen 473).
For more details on creating parenthetical references, see MLA Handbook, chapter 6, p. 213-232.