- Aegidius, Saint, Abbot1
- Agustín, Antonio, 1517-1586. Dialogos de medallas inscriciones y otras antiguedades1
- Alba, Fernando Alvarez de Toledo, duque de, 1507-15821
- Albizzi, Costanza1
- Aleramo, Marquis of Monferrato, -9671
- Alexander III, Pope, -11811
- Alexander VII, Pope, 1599-16671
- Alfonso II, King of Naples, 1448-14951
- Alfonso V, King of Aragon, 1396-14581
- Algebra1
- Amadori, Bartolomeo1
- Amadori, Lorenzo1
- Amadori, Niccolo1
- Angels1
- Animal culture1
- Antiphonaries1
- Antiquities1
- Apocryphal and legendary literature1
- Apologetics1
- Aqueducts1