A friend has made some nice slides that I could reuse (similar topics). He sent me the slides and commented that if I use them and could cite him that would be nice, I asked him how should I cite the slides but he said that whatever suits better to me he said "Just add my surname in some place where it's not very intrusive".
I'm not sure if he doesn't care or he doesn't want to be too picky, but I'd like to cite him, to each one his own.
AFAIK, they are related to a paper (but not in the paper) and to his thesis, where they could be as a diagram but definitively not animated. The slides (as such) may be available at some URL, he said they will be but they are not available yet (so I don't have the URL yet). If citing by the URL I guess I could use this: "How to cite a website URL?"
Should I cite slides? If yes, how?