Encyclopedias, Almanacs, Transcripts, and Maps
- Act, First
- Acta Apostolicae Sedis
- Action and Passion
- Action at a Distance
- Action Française
- Action Française
- Active Life, Spiritual
- Acton, Charles Januarius
- Acton, John Emerich Edward Dalberg
- Acts of the Martyrs
- Acts, Notional
- Acuña, Cristóbal de
- Aczél, Tamás
- Ad Bestias
- Ad Limina Visit
- Ad Majorem Dei Gloriam (A.M.D.G.)
- Ad Perennis Vitae Fontem
- Ad Regias Agni Dapes
- Ad Sanctam Beati Petri Sedem
- Ad Tuendam Fidem