MLA documentation: in-text citations 3
Example:

The student is quoting from page 187 of the following essay:

Pérez-Torres, Rafael. “Between Presence and Absence: Beloved, Postmodernism, and Blackness.” Tony Morrison’s Beloved: A Casebook, edited by William L. Andrews and Nellie Y. McKay, Oxford UP, 1999, pp. 179-201.

Amy describes the scars on Sethe’s back as a tree, which, as suggested by Rafael Pérez-Torres, transforms “the signs of slavery . . . into an image of fruition instead of oppression.” (187)

Amy describes the scars on Sethe’s back as a tree, which, as suggested by Rafael Pérez-Torres, transforms “the signs of slavery . . . into an image of fruition instead of oppression” (187).

When a quotation is run into the text of a paper, the parenthetical citation appears after the quoted material and before the sentence period.