| Author | Titles | 1.
| Old Yacht Club. Sirius Project (Cobh, Irlanda) | 1 | 2.
| Oldani, Alessandro | 2 | 3.
| Olden, Wolfgang Schulze, | 2 | 4.
| Oldenberg, Hermann | 2 | 5.
| Oldenburg, Claes, 1929-2022 | 11 | 6.
| Oldenburg, Maartje | 1 | 7.
| Oldenburg, Peter | 1 | 8.
| Oldenburg, Richard E. | 2 | 9.
| Oldenziel, Ruth | 1 | 10.
| Oldfield-Florescu, Sylvia May | 2 |
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