Psellus - On the Operation of Demons: Now Available!
At long last here is one of the best works I have read and edited. Originally translated from Greek to English by Collisson in the mid 1800s, Psellus' Socratic-style dialogue covers all the basics of demonology and then some in a compact form.
I definitely recommend this work to those who intend to delve into anything related to summoning or studying the demonic- the categorizations are all here (although some who believe in demons may not agree with the categories given.) Loosely speaking, we have here a reference to the concept of airy spirits as spoken of in other works of the era; elsewhere they are often regarded as natural, rather than demonic, forces. Psellus also alludes to the use of psychotropics in demonic possession as well as dementia but never quite regards them in their modern, secular form.