I just thought it would be useful-slash-interesting to take note of which books people have studied from and/or read. So, to start, I'll put down one book, and then you can put another book, and we'll each take turns posting one book at a time. For the sake of my own sanity, I put down a reason why I like the following book. Sure, it's generic, but so help me God... 
Mod(s), if this shouldn't be here, feel free to delete / move. I won't be offended whatsoever.

~ Dictionary of Angels: Including the Fallen Ones - Gustav Davidson
Like: not only does it have a list of all the angels (including the fallen ones) from various sources (e.g. Milton, Bible, etc.), whilst going through and defining them, the extent of their powers, and their ranks - it also contains an appendix with good information on various topics. For instance, the order of the ranks of angels (Seraphim, Cherubim, etc.).

Montague Summers: The Vampire: His Kith and Kin and The Vampire in Europe.

I think this ones are the best among books about real vampires, first of, the guy was a priest so he studied the deeds and traced the vampire lore throughout entire Europe and New World, although most of his cases were placed, oh what a surprise, in Balkan. He aproached the theme systematicaly, without emotions, so you forget he was a priest. His scholar nature offers so much more than other books do. Id recommend his books to anyone who has an interest in this theme, cause honestly, Im tired of folks thinking that vampires glow and stupidity as such.

[jordyn]

the mighty grimoire of spells and rituals, by Frater Malik;  from my dad, it was one of the first books i read and he gave me.  usual golden dawn style post gardner  seventies ceremonialism, if you call them, they will come.

Montague Summers: The Vampire: His Kith and Kin and The Vampire in Europe.

I think this ones are the best among books about real vampires, first of, the guy was a priest so he studied the deeds and traced the vampire lore throughout entire Europe and New World, although most of his cases were placed, oh what a surprise, in Balkan. He aproached the theme systematicaly, without emotions, so you forget he was a priest. His scholar nature offers so much more than other books do. Id recommend his books to anyone who has an interest in this theme, cause honestly, Im tired of folks thinking that vampires glow and stupidity as such.

THEY DON'T GLOW, THEY SPARKLE! DUUHHH!

uh, just kidding. Anyway, good suggestion. I'm with you in that people are so blindly obsessive that they'll let their fandoms cloud their judgment. 

The Goetia: The Lesser Key of Solomon - pretty standard. I think, though, that when you're reading this, you need to be armed with common sense - when not to do things, etc. It's more or less one of the most classic books on demonology, and I like that it gives the reader good information on the ways things work. A good read.

uh, just kidding? Anyway, good suggestion. I'm with you in that people are so blindly obsessive that they'll let their fandoms cloud their judgment. 

That doesn't apply just on literature  ....

uh, just kidding? Anyway, good suggestion. I'm with you in that people are so blindly obsessive that they'll let their fandoms cloud their judgment. 

That doesn't apply just on literature  ....

True, that.