Encyclopedias, Almanacs, Transcripts, and Maps
- Autotrophic Bacteria
- Avahis, Sifakas, and Indris: Indriidae
- Avalon, Arthur
- Avenar
- Aviation Physiology
- Aviation Regulatory Agencies
- Avichi
- Avogadro’s number
- Avram Noam Chomsky
- Awareness
- Awyntyrs off Arthure at the Tern Wathelyn
- Axel Fredrik Cronstedt
- Axinomancy
- Axiology
- Axion
- Aye-Aye: Daubentoniidae
- Aye-ayes
- Aye-Ayes
- Ayperor (or Ipès)
- Ayton, W(illiam) A(lexander) (1816-1909)