I've got a few books on psychic protection, but this one is definately my favourite.
It goes through every issue related to psychic disturbance I could possibly think of and manages to dicuss the relevant subjects in a chatty, but educated manner. Matthews manages to explain many sensitive issues in a way that keeps things light and entertaining.
I would recommend this book to anyone embarking on a spiritual lifestyle, or to anyone who often feels uncomfortable or scared sometimes without understanding why.