Hi
Jenny Randles wrote a book back in 1981 called UFO STUDIES, a Handbook for Enthusiasts.
The book is very informative and lays out recommended procedures for the investigation of paranormal events such as UFO's. She also gives tips on interview techniques and quotes several case studies. It gives advice on who to contact when evidence needs anylising, such as labs and universities etc.
The book could be called the UFO observers hand book and is a good read, i suspect it may not be in print now. It was published by Robert Hale, London.
Observer