Grab three great resources at wicked low prices! 

The Paranormal Pack sale includes the first two installments of the Haunted Tourist's Guide series as well as a resource on vampires and vampirism. All three works provide clear, succinct definitions on concepts, entities, and experiences you may encounter in the course of paranormal investigation - from the same person who brought you the Dictionary of Demons

Each of these make handy guides for your own research or can add a layer of verisimilitude to your paranormal worldbuilding.