APA, 6th edition
Personal communications may be interviews, private letters or e-mails, telephone conversations, and the like. Because they are not recoverable data, personal communications are not included in the reference list. Cite personal communications in text only. Give the initials and surname of the interviewee and as exact a date as possible. Either example below may be used.
R. L. Garza (personal communication, May5, 2010)
(K. D. Nguyen, personal communication, September 28, 1998)
Chicago, 16th edition (Humanities)
Personal communications may be interviews, private letters or e-mails, telephone conversations, and the like. Because they are not recoverable data, personal communications are not included in the reference list. Cite personal communications in text only. Citations should include names of both the person interviewed and the interviewer, the place and date. All formats below may be used.
1. Rita L. Garza (interviewee) in discussion with the author, May 2010.
2. Rita L. Garza, interview by Maximiliano Molina, May 5, 2010.
3. Molina, discussion; Nguyen interview.
MLA, 9th edition
Personal communications may be interviews, private letters or e-mails, telephone conversations, and the like. Because they are not recoverable data, personal communications are not included in the reference list. Cite personal communications in text only. The following forms may be used in the text.
In a conversation with R. L. Garza, (May 2010) . . .
According to a letter from K. D. Nguyen, in May 2010 . . .
Similar findings have been noted by Fletes (oral communication, September 2010)