| Author | Titles | | 1.
| Orangerie Unteres Belvedere (Viena, Áustria) | 1 | | 2.
| Oranje, Laurentien van | 1 | | 3.
| Orazi, Andrea Antonio, 1670-1749 | 1 | | 4.
| Orazi, Anna Maria | 1 | | 5.
| Orazi, Manuel | 1 | | 6.
| Orazio, Gaetano | 13 | | 7.
| Orazio-Ravel | 2 | | 8.
| Orbach, Gérard | 1 | | 9.
| ORBOK, Loran | 1 | | 10.
| Orchard Gallery (Derry, Grã-Bretanha) | 3 |
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