To create a reference for material sourced from a presentation or lecture, you need to follow the same basic format as for any other source, by asking yourself the following questions:
Here are some common examples.
1. PowerPoint presentation from a Design School lecture
Crowe, V. (2017). Ornament and crime. Retrieved from https://blackboard.vuw.ac.nz/webapps/blackboard/execute/content/file? cmd=view&mode=designer&content_id=_2042496_1&course_id=_90622_1.
NB: Providing a Blackboard page as a reference is fine if your paper is for an assignment that will only be seen by your lecturer. However, if your paper is going to be made available to the "outside world" e.g. published on a web site, then you need to reference the resource as an irretrievable personal communication. This also applies to statements made by a lecturer during class that are not retrievable in a written resource.
Personal communications include private letters and e-mail, personal conversations and phone calls. Personal communications are cited in text only and are not included in your reference list., When citing, give initials as well as the surname involved, and give as precise a date as possible e.g.:
Art Nouveau was often described as functionless and impractical (V. Crowe, personal communication, March 29, 2017).
2. Online presentation
Mairn, C. (2013). Makerspaces. Retrieved from https://www.slideshare.net/chadmairn/makerspaces-20805799.