| Eredivisie 1965/1966 - Appearances as Referee |  |
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| 20/03/1966 | ADO | - | GVAV Groningen | 0:0 | - | - | - |
| 01/05/1966 | FC Twente '65 | - | Feijenoord | 1:3 | - | - | - |
| Eredivisie 1965/1966 - Appearances as Referee | |
|
|
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| 20/03/1966 | ADO | - | GVAV Groningen | 0:0 | - | - | - |
| 01/05/1966 | FC Twente '65 | - | Feijenoord | 1:3 | - | - | - |
| Complete name: | Gerard Klaassens |
| Born: | 07/02/1931 |
| Place of birth: |
Netherlands |
| Residence: | Venlo |
| Nationality: |
Netherlands |