| Europa League 1968/1969 - Appearances as Referee |  |
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 |
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| 30/09/1968 | Greenock Morton FC | - | Chelsea FC | 3:4 | - | - | - |
| 02/04/1969 | Athletic Bilbao | - | Rangers FC | 2:0 | - | - | 2 |
| Europa League 1968/1969 - Appearances as Referee | |
|
|
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| 30/09/1968 | Greenock Morton FC | - | Chelsea FC | 3:4 | - | - | - |
| 02/04/1969 | Athletic Bilbao | - | Rangers FC | 2:0 | - | - | 2 |
| Complete name: | Wilhelmus Jacobus Maria Schalks |
| Born: | 21/03/1923 † 25/10/2017 |
| Place of birth: |
Leiden, 
Netherlands |
| Residence: | Leiden |
| Nationality: |
Netherlands |