[Event "IBM"]
[Site "Amsterdam"]
[Date "1970.07.14"]
[Round "1"]
[White "Donner, Jan Hein"]
[Black "Jongsma, Alexander"]
[Result "1/2-1/2"]

1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. Nf3 e6 5. Bg5 dxc4 6. a4 Qa5 7. Bd2 Bb4 8. e4 c5 9. Bxc4 cxd4 10. Nxd4 Qc5 11. Bb5+ Nbd7 12. Nb3 Qd6 13. Qe2 O-O 14. f4 e5 15. O-O a6 16. Bc4 Nb6 17. fxe5 Qxe5 18. Bf4 Qh5 19. e5 Qxe2 20. Bxe2 Nfd5 21. Bd2 Be6 22. a5 Bxc3 23. bxc3 Nd7 24. c4 Ne7 25. Nd4 Nxe5 26. Nxe6 fxe6 27. Rfb1 N7c6 28. Rxb7 Nd4 29. Bf1 Nef3+ 30. gxf3 Nxf3+ 31. Kh1 Nxd2 32. Bh3 Rf6 33. Rg1 g6 34. Re7 Nxc4 35. Bxe6+ Rxe6 36. Rxe6 Kf7 37. Rc6 Nxa5 38. Rc7+ Kf6 39. Rb1 Re8 40. Rb6+ Re6 41. Rxe6+ Kxe6 42. Rxh7 Nc4 43. Rg7 Kf5 44. Rc7 Ne5 45. Ra7 Nd3 46. Rxa6 Nf4 47. Kg1 Kg4 48. Ra3 g5 49. Kf2 Nh5 50. Rf3 Nf4 51. Rg3+ Kf5 52. Kf3 Nh5 53. Rg2 Nf6 54. Ra2 Kg6 55. Ke3 Kh5 56. Kf3 Kg6 57. Ra8 Kf5 58. Ra5+ Kg6 59. h3 Kh5 60. Ra6 Kg6 61. Ke3 Kf5 62. Ra5+ Kg6 63. Kd4 Ng8 1/2-1/2