I think that there are some good books published by Llewellyn, but you have to dig deep, for a long time to find them. I would like to read some more advanced books, but I have to admit that I'm uncertain about what should be included in them. When one advances in the Craft, we often go our own ways and focus on different areas like herbology, divination, crystals, etc. Most "advanced" Witches write their own rituals and have found a pantheon they are comfortable with, we not only know what tools are but how to make them, and which ones work for us or not. I think some memoirs of some advanced modern Witches could be very insightful, and help advanced students.