For most research topics, peer-reviewed, published, easily accessible sources are ideal. However, sometimes the most relevant information can be found in sources that aren't published or peer-reviewed, such as memos. In fact, memos are good examples of primary or field research, meaning that the sources are directly related to the topic and were not second-hand accounts. Most of the major citation styles include guidelines for citing memos.
The entry for an unpublished memo on the Works Cited page begins with the author's name, the words "Letter to" or "Memo to" and the recipient(s), the date, and the medium. For example: Smith, John Q. Memo to Diane Jones. 6 Oct. 2011. Email. An in-text citation would contain the author's last name, and page numbers if available, in parentheses. Published memos and letters are cited as works within a collection or articles on a webpage or in a database, depending on how it is accessed.
Unlike other citation styles, APA style instructs writers to leave personal communications, including memos, off of the references list; however, an in-text citation is required. For example, your paper might paraphrase an idea from a memo and cite it in this way: John Q. Smith recommends that employers reduce meeting times to 45 minutes from an hour (J. Smith, personal communication, October 6th, 2011).
Communications that have been published in collections or on databases should be included in the references. Use the guidelines for works within collections or articles in databases to document them.
Chicago Guidelines: The Footnote
Chicago citations require both a footnote in the text and an entry in the bibliography. What information goes in the footnote and bibliographic entry depends on how the memo or letter was delivered (medium), and if it is part of a collection. A note for a basic print letter or memo includes the original author's name, the recipient's name with the word "to," and the date. For example, a note would read: 1. John Q. Smith to Diane Jones, Oct. 6th, 2011.
Chicago Guidelines: Bibliography Entry
The bibliography entry contains the same information, but also includes the city and state before the date. The bibliography entry would read: Smith, John Q. John Q. Smith to Diane Jones, Dallas, TX, Oct. 6th, 2011. An emailed memo would include the words "email message to" before the recipient's name in both the footnote and the bibliography entry.