| Europa League 1972/1973 - Appearances as Referee |  |
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| 20/09/1972 | FC Porto | - | FC Barcelona | 3:1 | - | - | - |
| Europa League 1972/1973 - Appearances as Referee | |
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| 20/09/1972 | FC Porto | - | FC Barcelona | 3:1 | - | - | - |
| Complete name: | Karl Keller |
| Born: | 01/04/1923 |
| Place of birth: |
Switzerland |
| Residence: | Basel |
| Nationality: |
Switzerland |