| Europa League 1983/1984 - Appearances as Referee |  |
 |
 |
||||
| 13/09/1983 | Trabzonspor | - | Inter | 1:0 | - | - | - |
| 22/11/1983 | Bayern München | - | Tottenham Hotspur | 1:0 | - | - | - |
| Europa League 1983/1984 - Appearances as Referee | |
|
|
||||
| 13/09/1983 | Trabzonspor | - | Inter | 1:0 | - | - | - |
| 22/11/1983 | Bayern München | - | Tottenham Hotspur | 1:0 | - | - | - |
| Complete name: | Johannes Nicolaus Ignacius Keizer |
| Born: | 06/10/1940 † 18/11/2024 |
| Place of birth: |
Volendam, 
Netherlands |
| Nationality: |
Netherlands |