[Event "IBM"]
[Site "Amsterdam"]
[Date "1970.07.17"]
[Round "4"]
[White "Jongsma, Alexander"]
[Black "Hartoch, Robert G"]
[Result "1/2-1/2"]

1. d4 Nf6 2. Nf3 g6 3. c4 Bg7 4. Nc3 c5 5. e3 O-O 6. Be2 cxd4 7. Nxd4 Nc6 8. O-O d6 9. b3 Bd7 10. Bb2 a6 11. Qd2 Rb8 12. Nf3 Bg4 13. Rfd1 Qa5 14. h3 Bxf3 15. Bxf3 Rfc8 16. Rac1 b5 17. cxb5 1/2-1/2