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