Perhaps he is self taught?
Mark Danilovich Tseitlin is an Israeli International Grandmaster of chess of Russian origin. Mark Tseitlin got acquainted with chess in Leningrad's Pioneers Palace. He is self-taught, having studied without a coach. His peak FIDE rating was 2545 in 1995. He was awarded the title of International Master in 1978, and became a ...
https://en.wikipedia.org/wiki/Mark_Tseitlin