"The occult, in the broadest sense, is a category of esoteric supernatural beliefs and practices which generally fall outside the scope of religion and science, encompassing phenomena involving otherworldly agency, such as magic, sorcery, and mysticism and their varied spells." - Wikipedia
This is where you'll find any and all books that encompass the more detailed and intricate work of esoteric practices. Books on topics like the Golden Dawn, Hermeticism, Gnosticism, Enochian works, the history of witchcraft and other detailed accounts and/or stories by some of the biggest and most respected figures in these fields such as Aleister Crowley, Dr. John Dee, Alice Bailey, A. E. Waite, Cornelius Agrippa and more.