Books friendly to self-studying Industrial Organization
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.