Over the years I spend a couple of thousand Euros on chess books. My library contains a few gems like Rubinstein’s “Lärobok I Schack” (in swedish) and Bogoljubov’s “Die Moderne Eröffnung 1. d2-d4!”, but overall I bought a lot of crap and a couple of years ago I decided to throw away a lot of worthless opening books to make space. There were a couple of obvious keepers though:
Note: “Questions of Modern Chess Theory” was translated and republished by Quality Chess, but without the section on the Ragozin. Yes, it is outdated, so why not sell a second book?