If you are interested in this type of subject matter, even if you are a skeptic, you should read Strange Secrets: Real Government Files on the Unknown by Nick Redfern
This guy has gone through government archives, of the UK as well as the US on many subjects from Noah's Ark to UFOs and cattle mutilations, to obtain the information for this book. Although it contains some of his personal conjecture it has photocopies of some of the original documents. It's written in a pretty easy to read manner.
You can find it on Amazon for ~$11.