I have Position Play for High Runs. Read it years ago, how long ago, I can't even remember. I learned a bunch from Goerge Fels's Mastering Pool. Guys in the pool room looked at it and said that it had stuff in it that they had never heard of/learned in all the years they'd played, and some of them had been playing a hell of a lot longer than me.
Blackjack reminded me that I have always had a tendency to over hit break shots. The first line in George's book, after the Preface: "I'm sorry, but I'll just bet that you're hitting the balls too hard."