Michigan's Otherside Paranormal Forums

If you want to have a complete understanding of all aspects of paranormal claims I have to recommend this. Its page after page of interesting articles.
This isn't a book, its a series of online articles that I would recommend to all Investigators. This is probably the best explanation of Orbs I have found online. They go into all aspects of what people claim to capture in photos. This explains why doors can open and close. This has got to be the best article touching on all aspects of paranormal I have read. If you read this you will became a better investigator and have more knowledge of claimed paranormal. You will have a better understanding of why people make different claims.

http://www.assap.org/index.html

great post. I've stumbled onto this site a few times. This certainly looks like the motherload of info!