| KNVB beker 1970/1971 - Appearances as Referee |  |
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| 16/08/1970 | Holland Sport | - | RBC Roosendaal | 4:0 | - | - | - |
| 08/11/1970 | AVC Heracles | - | AFC Ajax | 0:3 | - | - | - |
| 07/04/1971 | Feijenoord | - | AFC Ajax | 1:2 | - | - | - |
| KNVB beker 1970/1971 - Appearances as Referee | |
|
|
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| 16/08/1970 | Holland Sport | - | RBC Roosendaal | 4:0 | - | - | - |
| 08/11/1970 | AVC Heracles | - | AFC Ajax | 0:3 | - | - | - |
| 07/04/1971 | Feijenoord | - | AFC Ajax | 1:2 | - | - | - |
| Complete name: | Johannes Nicolaus Ignacius Keizer |
| Born: | 06/10/1940 † 18/11/2024 |
| Place of birth: |
Volendam, 
Netherlands |
| Nationality: |
Netherlands |