How to cite a deck of powerpoint slides with two titles?
This should be applicable for your problem in APA sytle.


  [Authors (if known)]. [Title of the matter]. Retrieved from [URL]. Slides [start]-[end].


Just keep in mind that the main purpose of citation is to facilitate the reader to be able to refer the materials you've referred. As long as you show clearly where to look and what to look for, your citation is considered valid. Citation formats are there for uniformity within the bibliography within the concerned journal.