Your own personal notes from a professor's lecture
In APA style, lecture notes are considered personal communication. Therefore, they do not appear in the References list, and are referred to in the body of the paper only.
Example:
Nepean, G. (2015). Ownership structures in mass communications [PowerPoint Slides]. Retrieved from http://www.onlineguelphhumber.ca/
In-text citation:
Paraphrase: (Nepean, 2015).
Direct quote: (Nepean, 2015, slide 6).
For PowerPoint slides, use the name of the presentation as the title.