Angelology.
A Dictionary of Angels, including the fallen angels by Gustav Davidson
Angels and Angelology in the Middle Ages by David Keck
Angel Magic. The Ancient Art of Summoning and Communicating with Angelic Beings by Geoffrey James
Angelology Satanology And Demonology
The 72 angels of the name - calling on the 72 angels of God by Kadmon Baal
The Angelical Language, Volume I. The Complete History and Mythos of the Tongue of Angels by Aaron Leitch
The Angelical Language, Volume II. An Encyclopedic Lexicon of the Tongue of Angels by Aaron Leitch
The representation of angels and angelic orders from the late miggle ages