This is a practical concern for the keyword searcher. The book was originally published by Simon & Schuster and later by David McKay. The copyright has lapsed in some jurisdictions, but not all.
In the digital age, where chess engines calculate 30 moves deep and cloud databases track millions of games, it is easy to overlook the golden era of chess literature. Yet, for the dedicated student of the game, certain classic texts remain irreplaceable. One such gem is by the legendary International Master I.A. Horowitz. Chess Openings Theory And Practice Horowitz.pdf