Korchnoi vs B Djurasevic, 1956  (E30) Nimzo-Indian, Leningrad, 25 moves, 0-1 NN vs Bronstein, 1961  (E30) Nimzo-Indian, Leningrad, 19 moves, 0-1 Spassky vs Tal, 1973  (E30) Nimzo-Indian, Leningrad, 38 moves, 0-1 A Lukin vs Karpov, 1967  (E31) Nimzo-Indian, Leningrad, Main line, 58 moves, 0-1 A H Williams vs Karpov, 1974  (E31) Nimzo-Indian, Leningrad, Main line, 30 moves, 0-1 W Schmidt vs P Enders, 1981   (E31) Nimzo-Indian, Leningrad, Main line, 29 moves, 0-1 6 games