Answered By: Gabe Gossett Last Updated: Jan 14, 2016 Views: 1220
The APA Manual does not give good guidance on citing lectures that cannot be referred back to through some form of documentation. The best thing to do is to check with your professor about how they would prefer you to handle such citations.
That said, a good approach would be to treat the lecture as personal communication. Personal communication should only be cited in the text of your paper and not be included in the reference list (because it can not be referred back to). If there is a recording or slides you should refer to those documents. If your professor has publicly uploaded the presentation to YouTube, Slide Share, or any other publicly accessible site (meaning, something you can get to without logging into anything) then you should cite that source as an internet document.
Personal communication should be cited in the following format, pretending that we are referring to a lecture by someone named Paul Piper:
This would be the sentence you wrote in your paper where you would want your citation (P. Piper, personal communication, October 15, 2011).
More details are in the APA Manual on p. 179.