From the Purdue OWL:
"Personal interviews refer to those interviews that you conduct yourself. List the interview by the name of the interviewee. Include the descriptor Personal interview and the date of the interview."
Example: Smith, Jane. Personal interview. 19 May 2014.
If you're looking for an expert source:
If you're looking for someone who is not an expert about your topic:
You can always come up to the library reference desk for help! We will happily sit down with you and make a list of people you could contact to interview. Depending on your topic, you might even be able to interview a librarian!
Additionally, you could use Ask a Librarian, or email Emily directly, to get help from a librarian without coming up to the library.