Encyclopedias, Almanacs, Transcripts, and Maps
- Arnau de Villanova
- Arno Allan Penzias
- Arnold Johannes Wilhelm Sommerfeld
- Arnold Joseph Nicholson
- Arnoux, François (ca. 1622)
- Arnuphis (ca. 174 C.E.)
- Around the World Beneath the Sea: The USS Triton Retraces Magellan's Historic Circumnavigation of the Globe
- Arphaxat
- Arriola, Pepito (1896-1954)
- Arrow Worms
- Arrow worms
- Arrow Worms: Chaetognatha
- Arroyo, Stephen (1946-)
- Ars Notoria
- Art Forgery
- Art Identification
- Artemidorus Daldianus
- Artemisia of Caria
- Artemisian Order
- Artephius (d. ca. 1119)