| Autor | Títulos | | 1.
| Horton, Charles | 2 | | 2.
| Horton, Kristan, 1971- | 1 | | 3.
| Horton, W. Claude | 1 | | 4.
| Hortus Regius Botanicus Kewensisrdens (Grã-Bretanha) | 0 | | 5.
| Ver: Grã-Bretanha. Royal Botanic Gardens (Kew) | 2 | | 6.
| Horvat, Frank, 1928- | 3 | | 7.
| Horváth, Hilda | 3 | | 8.
| Horvath, James | 5 | | 9.
| Horvatic, Darja | 1 | | 10.
| Horville, Robert | 1 | | 11.
| Horvitz, David, 1982- | 1 |
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