Books friendly to self-studying Industrial Organization I'm currently an undergraduate freshman looking for resources to self-read Industrial Organization. I've read Varian's undergraduate book cover-to-cover and have a decent understanding of basic game theory, and I own the book 
Industrial Organization: Theory and Applications by Pepall-Richards-Norman

Is there another book that would be better for someone who wants a rigorous treatment of IO that is mathematically advanced but theoretically digestable, or is this one optimal? (By the time I begin to self-read, I'll have finished most of baby Rudin).
While taking Industrial Organization I remember working with:


Strategies and games: theory and practice by Dutta
Introduction to industrial organization by Cabral
Industrial organization: theory and applications by Shy
Industrial Organization: Markets and Strategies by Belleflamme and Peitz


The first two are rather introductory while third and forth are more advanced (getting into greater detail with a little bit more advanced maths). You can probably find them online if you try.

And on top of that, I really enjoyed The Economics of industrial organization by Shepherd. It is way older than the others but still made quite a good read.