From my library
Well...some very rare, and very expensive. The Zukertort book between 500-700 USD ! Why? Because is one of the best chess book of all time. I can't explain why and who is fabulous author Jimmy Adams in a post reply of few words. All the same for Goldman, Skinner and Vorhoeven, or Richard Forster!
One certainty: They do not write these " imbeciles"books of "How to smash something ...", "Chess Assassin", "The Killer Chess Opening ..." Dismantig ... something " , "Beat the Guerillas", and so on!
What is the best two or three hard-cover books you have and go into them often?
regards