Personal communications may include private letters, memos, electronic communication (i.e., email messages), personal interviews or telephone conversations that you may wish to include in your manuscript. Unlike standard references to published journal articles, books and websites, the defining characteristic of a personal communication is that it does not provide recoverable data. For example, a reader of your article will not be able to access a transcript of a phone conversation you had with your colleague. As a result, personal communications must be cited differently than published sources included in your reference list.
The first step towards accurately citing a personal communication is to read your target journal’s guidelines to learn if personal communications are accepted. For example, Nature Communications allows the citation of personal communications (with a statement of permission from the quoted individual), but Science does not.
Since these types of communication are not recoverable data, personal communications should not be included in your reference list; they must be cited in-text only. This is commonly accomplished using parenthetical citations, where it is essential to include the words “personal communication” and the exact date that the communication occurred. For example:
Our results are consistent with ongoing research conducted in the northern Rocky Mountains (J. Smith, personal communication, July 8, 2019).
However, when referencing the source of your personal communication in the text, you do not need to include the source’s name in the parenthetical citation. Here is an example:
Research results obtained by J. Smith in the northern Rocky Mountains are consistent with our findings (personal communication, July 8, 2019).
Importantly, different journals may have variable preferred formats for the citation of personal communications. It is important to ensure that you comply with your target journal’s preferred format. Finally, remember that any personal communication included in your manuscript must have scholarly relevance.