One of my favourite unusual books is "A Treatise on White Magic" by Alice Bailey, 1934.
Another wacky one: "The Ancient Science and Art of Pranic Healing (practical manual on paranormal healing)" by Choa Kok Sui.
And "Talk does not cook the rice" a commentary on the teaching of Agni Yoga by Guru RHH.
And "Choirs of the God- revisioning masculinity" edited by John Matthews (an internationally acknowledged authority on the Arthurian and Grail legends).
Bonkers, but fascinating

Go on, 'fess up!