In another thread someone mentioned how Gallery of Magick books are lacking context and only include specific instructions. The same goes for NAP. There's not any background concerning the angels that are being evoked. I'm curious myself, and for those also curious, does anyone know what sourcebooks the GoM books and NAP reference for their systems? If you don't know the exact ones, can you name some books that deal with angelic evocation in more detail?
I've found those books to be valuable resources but I'm looking to learn more about angelic evocation.