| Author | Titles | | 1.
| Firmery, Joseph Léon | 1 | | 2.
| Firmin, Stanley | 1 | | 3.
| Firmin-Didot, Ambroise, 1790-1876 | 2 | | 4.
| Firmino, Almeida, 1934-1977 | 1 | | 5.
| Firmino, João | 2 | | 6.
| Firmino, Jorge, 1973- | 1 | | 7.
| Firmino, Nicolau, 1907-2001 | 21 | | 8.
| Firmo, Catarina | 1 | | 9.
| Firmo, Joaquim Ferreira dos Santos | 2 | | 10.
| Firmo, Luís | 5 |
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