Reading Comprehension, eBooks, and Libraries

I've completed two books recently: Robert A. Heinlein's Stranger in a Strange Land and Frank Herbert's Dune: Messiah . Following my completion of said books, it occurred to me that though Herbert's was certainly shorter than Heinlein's, I felt I retained more information from the latter. The one difference that I could think of is that I read Dune as an ebook and Stranger as a paperback. A quick…