Borislav Ivkov was a Serbian chess Grandmaster. He was a World championship candidate in 1965, and played in four more Interzonal tournaments, in 1967, 1970, 1973, and 1979.

Paul Keres was an Estonian chess grandmaster and chess writer. He was among the world's top players from the mid-1930s to the mid-1960s, and narrowly missed a chance at a World Chess Championship match on five occasions. As Estonia was repeatedly invaded and occupied during World War II, Keres was forced by the circumstances to represent the Soviet Union and Nazi Germany (1941–44) in international tournaments.