There are several styles in which works can be cited.
Looking at the various categories given in the APA formatting and style guide, a Q&A page should be cited as an Online Forum or Discussion Board Posting. The citation for the page should include the title of the message which would be the question posted, and the URL of the relevant Q&A page. The title of the items should not be italicized. As the author's name is not available here, the screen names provided can be used. The date on which the response was posted should also be included.
justaguide(2011, November 29). Is it possible to cite a Q&A page? Message posted to http://www.enotes.com/enotes-sources/q-and-a/possible-cite-q-and-page-298346.
Using the MLA format for citing a website page, list the alias used by the authors here followed by information of the web site. Use eNotes as the publisher name and n.d. as there is no date of publishing, provide the date on which the response was posted.
justaguide, "Is it possible to cite a Q&A page?" enotes.com. eNotes, n.d. Web. 30 Nov. 2011.