Yes, the Book of the SubGenius is a perfectly acceptible source. It is the defining document of the church. Saying that you can't use it would be like saying the Christian articles can't use the Bible or that Islamic articles couldn't cite the Koran. It's explicitly allowed under WP:V to use self-published and/or self-descriptive works in articles about the work itself or the organization which produced them. Don't let the NLOleson's of the world push you around. -    