Works that cannot be accessed by readers are cited only in the text as personal communications; they are not included in the reference list. Personal communications include private letters, text messages, memos, online chats or direct messages, emails, (telephone) conversations, personal interviews (i.e., not conducted in the context of research), unrecorded webinars or classroom lectures, and so on.
Works that are only accessible to your specific reader group (and not to the general public) should not be treated as personal communication. Consider, for example, a PowerPoint presentation or a recorded lecture posted on a digital learning environment (such as Canvas).
When citing personal communication, provide initials and surname (in that order) of the person in question, followed by the words “personal communication” and the exact date (month/day/year):