Encyclopedias, Almanacs, Transcripts, and Maps
- Australian Robins (Petroicidae)
- Australian Toadlets and Water Frogs (Myobatrachidae)
- Australian Warblers (Acanthizidae)
- Australo-American Sideneck Turtles (Chelidae)
- Austronesian languages
- autochrome
- Automobile Emissions
- Avahis, Sifakas, and Indris (Indriidae)
- Avian Flight
- Avian Migration and Navigation
- Avian Song
- Aviation Fuel
- Avraham ben David of Posquières
- Axis Mundi
- Aye-Ayes (Daubentoniidae)
- Ayub Khan, Muhammad
- Aztec Religion
- B?dar?ya?a
- B?r?n?, al-
- Ba?ye Ibn Paquda