[Event "IBM"]
[Site "Amsterdam"]
[Date "1969.??.??"]
[Round "1"]
[White "Donner, Jan Hein"]
[Black "Ree, Hans"]
[Result "1/2-1/2"]

1. c4 Nf6 2. d4 c5 3. d5 d6 4. Nc3 g6 5. e4 Bg7 6. Be2 O-O 7. Nf3 e6 8. O-O exd5 9. cxd5 Re8 10. Nd2 Na6 11. f3 Nc7 12. a4 Nd7 13. Nc4 Ne5 14. Ne3 f5 15. f4 Nf7 16. exf5 gxf5 17. Nc4 b6 18. Be3 Bb7 19. Qd2 Bxc3 20. bxc3 Nxd5 21. Bf3 Nxe3 22. Nxe3 Bxf3 23. Rxf3 Nh6 24. Nxf5 Nxf5 25. Qd5+ Kh8 26. Qxf5 Qe7 27. Rd1 Rad8 28. c4 Qe6 29. Qd3 Qg6 30. f5 Qf6 31. Re3 Re5 32. Rxe5 Qxe5 33. Qf3 Re8 34. f6 Rf8 35. f7 Kg7 36. Rf1 Qe6 37. Qg3+ Kh8 38. Qc3+ Qe5 39. Qf3 Kg7 40. h3 h6 41. Kh1 1/2-1/2