According to the Publication Manual of the American Psychological Association (6th edition), the citation for a personal conversation includes details about the source, the type of communication and the date it occurred. Unlike references to other kinds of sources, the source's first initial appears in the citation as well. For example:
(I. Smith, personal conversation, March 3, 2013)
This type of format applies not only to personal conversations, but also to interviews, memos, emails and phone conversations.
The entries on the References page at the end of your paper give bibliographical information about the sources you cite so readers can find those sources if they so desire. Unlike books, periodicals and Web pages, personal conversations, interviews, letters and the like do not contain information a reader typically can go find, so these sources do not appear on the References page. Instead, the in-text citation contains all the necessary details about the source.