Huge plus one for OS: Three Easy Pieces. It sticks in my memory forever and I just confirmed, I had a random question about "why" from part of that book in 2014 and emailed Remzi and within a few days had a very detailed response back. It was much appreciated because I can get hung up on little details that I can't explain and it can really create a wall for me, so thanks Remzi for being responsive to a learner!
