@billturner I'm in full agreement re paper vs PDF BUT PDFs are great for looking up specific facts, and the books don't have an index! 🙀
[edit: correction v2.5 ("revised and expanded") DOES have an index]
Also, there's no legal source for them, which means that the only source we do have may dissappear at any moment. SO… even if you don't intend to read them now, you might want to grab a copy for later. ;)