Background Info on Djinn, Spirits, Magic...
This is what Jonathan has tto say on the magical research he did for the books:

"The magic and spirits in the book are a mix of stuff that I invented and things that I pinched from folklore, myth and legend. I suppose it could be possible to invent an entirely new magical system, but it would be astonishingly hard. For instance, Tolkien, who is revered for the completeness and originality of his world, nicked masses himself from Northern myths and legends especially. In practise any writer of fantasy is going to use certain concepts that have been handed down, firstly from oral tradition and then more recent literary works. The key is: is he/she going to be able to infuse them with something original? If not, it will seem at best a bit hackneyed. So a writer must walk a fine line - borrow things where appropriate, but give it something new as well. I have read a lot about these subjects over the years, and I had reference books about when I was writing, but I was careful not to over-research - the danger there is that you lose all spontenaity. If you look at the magic in my book there isn't much detail about the mechanics of it, because that's not the interesting thing to me. I'm interested in the characters and the implications of the master/servant relationship.
.....
Jabor, with his jackal head is influenced by the Egyptian god Anubis."

So, here you can read about the original mythology and ideas that Jonathan adopted and changed for his books.

Origins of the Idea of Djinn and Aladdin/Al-Haddin

Iblis

Afreets

Anubis

Golems

Prague, Alchemy, and Golden Lane

Amulets

Coptic

Samarkand

The Ptolemy Dynasty