According to APA style, an interview you conducted is considered "personal communication," much like an email. In the body of your paper, you may use a parenthetical citation such as (B. Billiken, personal communication, November 15, 2010). The interview will not appear on the References page.
If you have any questions, please drop by Circulation Desk on the 1st floor of Pius Library to consult the Publication Manual of the American Psychological Association, 7th edition. https://libcat.slu.edu/record=b4719855~S5
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