Morgan explained that the most effective method for his study was a combination of online surveys and face-to-face interviews.
Explain
Cite personal letters, personal interviews, e-mail messages, and social media posts by the name listed in the works cited entry, as for any other sources.
Identify the type of source in your text if you feel it is necessary for clarity.
Works cited entry
Morgan, Sean. “Re: Study methods.” Received by Sean Brannon, 15 Mar. 2014.