Personal Communication includes: private letters, memos, some electronic communication (i.e. email or messages from nonarchived discussion groups), personal interviews, telephone conversations, etc.
These types of communication are not recoverable data and therefore should not be included on the Reference page.
Cite personal communications in text or as a footnote.
Mark Johnson said in an email to the author, John, he ...
¹Terry O'Kelly, e-mail message to author, June 6, 2009.