[Event "IBM"]
[Site "Amsterdam"]
[Date "1970.07.20"]
[Round "6"]
[White "Tringov, Georgi Petrov"]
[Black "Donner, Jan Hein"]
[Result "1/2-1/2"]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Bg5 e6 7. f4 Be7 8. Qf3 Qc7 9. O-O-O Nbd7 10. g4 b5 11. Bxf6 Nxf6 12. g5 Nd7 13. f5 Nc5 14. f6 gxf6 15. gxf6 Bf8 16. Qh5 Bd7 17. Bh3 b4 18. Nce2 O-O-O 19. Qxf7 Bh6+ 20. Kb1 Rdf8 21. Qe7 Re8 22. Qf7 Ref8 23. Qh5 Rxf6 24. Rhf1 Rhf8 25. Rxf6 Rxf6 26. Qh4 Rg6 27. Nb3 Bg5 28. Qxh7 Rh6 29. Qg7 Nxe4 30. Ng3 Rxh3 31. Nxe4 Rxh2 32. Nd4 Bd8 33. Qg3 Rh5 34. Nxd6+ Kb8 35. Nb3 Be7 36. Qg8+ Ka7 37. Nc4 Bb5 38. Qg1+ Kb8 39. Qg8+ Ka7 40. Qg1+ Kb8 41. Qg8+ Ka7 1/2-1/2