Information abounds on the occult and paranormal studies (ranging from decent science to
wishful thinking). Depending on what you're looking for, there are a variety of sources to consider.
If you're looking for scientific information, there isn't any. Every study thus far has at least seriously brought occultism into serious question, if not proved it did not exist outright. There are a few things in the field of quantum mechanics which might suggest some sort of "spookiness" but there's nothing
conclusive by a long shot.
If you're looking for serious, philosophic and theological work on occultism, you're best bet is to try and find information put out by various groups:
Isaac Bonewitts is a good source for neo-paganism.Consult the works of Carl Jung, Israel Regardie and Lon Milo Duquette for interesting material on modern ritual craft.
Peter Carroll is a great source for "Chaos Magic", the study of magic without any religious contextAnd on, and on and on...A great general reference is going to be the internet Sacred Text Archive, which covers material ranging from Christianity to African shamanism,
Qabalah, alchemy, numerology, Astrology, and more.