From the textbook, Operating Systems: Three Easy Pieces, there are readings that address the concepts we discuss in class (and sometimes implement in projects). Reading these can fill in details and provide another perspective to understand the design and implementation questions.
Introduction / Overview: Chapter 2, through (and including) Section 2.6.
Processes: Chapters 4 through 7. Chapters 8 and 9 go beyond what we have covered, so explore them, too, just for the fun of it!
Virtual memory: Chapters 13 through 23. This is a lot of material, including what we covered plus more depth and detail. Note the dialog in Chapter 24, concerning all of the virtual memory chapters, which begins:
Student: (Gulps) Wow, that was a lot of material.
Professor: Yes, and?
Student: Well, how am I supposed to remember it all? You know, for the exam?
Professor: Goodness, I hope that's not why you are trying to remember it.
Student: Why should I then?
Professor: Come on, I thought you knew better. You're trying to learn something here, so that when you go off into the world, you'll understand how systems actually work.
File systems: Chapters 36, and 39 through 42. There's again lots of detail here, some of it more intricate because it involves real systems, but you should be able to see the similarities to our simplified block device and file system.