Chess right of a deposed champion to a rematch, and the next champion, Armenian Tigran Petrosian, a player renowned for his defensive and positional skills, held the title for two cycles, 1963–1969. His successor, Boris Spassky from Russia (champion 1969–1972), won games in both positional and sharp tactical style. The next championship, the so-called Match of the Century, saw the first non-Soviet challenger since World War II, American Bobby Fischer, who defeated his Candidates opponents by unheard-of margins and clearly won the world championship match. In 1975, however, Fischer refused to defend his title against Soviet Anatoly Karpov when FIDE did
Bobby Fischer Teaches Chess the work". According to Margulies, Fischer wanted a high quality work free of any errors, so Michael Valvo and Raymond Weinstein were brought in as proof readers. Chiefly due to its accessibility for beginners and Fischer's high public profile, the book sold an estimated one million copies. It is difficult to determine chess book sales with certainty, but this figure, based on the royalty payments made to co-author Stuart Margulies, makes it a candidate for best-selling chess book of all time. In October 1972, following Fischer's victory in the World Championship, the Bantam edition appeared on the New York Times