The MLA format template calls for a period after the title of a source, but if the title of a source ends in a question mark or exclamation point, do not include a period. Question marks or exclamation points, as stronger marks, always supersede a period:

Albee, Edward. Who’s Afraid of Virginia Woolf? Signet, 1983.

If, however, the title of the container ends in a question mark or exclamation point, do add a comma after the question mark. MLA style allows a comma after a question mark or exclamation point if the comma facilitates reading or if rewording is impossible. Since a works-cited-list entry cannot be reworded and since the MLA template calls for a comma after the title of a container, retain the comma:

Tomlinson, Hugh, and Graham Burchell. Translators’ introduction. What Is Philosophy?, by Gilles Deleuze and Félix Guattari, Columbia UP, 1994.