How about the UFO Investigator's Manual: UFO investigations from 1892 to the present by Nigel Watson.
From Haynes Publishing UK: (and you thought they only published car and truck manuals.....)
"UFOs have been a global phenomenon from the late 19th century to the present day, and this Haynes Manual will examine many UFO investigations worldwide by looking at the government reports both official and secret that have attempted to explain the otherworldly. This Manual will also explain how you can identify a UFO yourself and how to classify an alien encounter was it of the first, second, third, fourth or fifth kind? The findings of scientific research will also be explored, as will the human attempts at alien communication, and, finally, alternative explanations of uncanny happenings
The 37th Parallel: The Secret Truth Behind America's UFO Highway by Ben Mezrich.
From the publisher, Simon and Schuster:
"Like “Agent Mulder” of The X-Files, computer programmer and sheriff’s deputy Zukowski is obsessed with tracking down UFO reports in Colorado. He would take the family with him on weekend trips to look for evidence of aliens. But this innocent hobby takes on a sinister urgency when Zukowski learns of mutilated livestock, and sees the bodies of dead horses and cattle—whose exsanguination is inexplicable by any known human or animal means.
Along an expanse of land stretching across the southern borders of Utah, Colorado, and Kansas, Zukowski discovers multiple bizarre incidences of mutilations, and suddenly realizes that they cluster around the 37th Parallel or “UFO Highway.” So begins an extraordinary and fascinating journey from El Paso and Rush, Colorado, to a mysterious space studies company and MUFON, from Roswell and Area 51 to the Pentagon and beyond; to underground secret military caverns and Indian sacred sites; beneath strange, unexplained lights in the sky and into corporations that obstruct and try to take over investigations. Inspiring and terrifying, this true story will keep you up at night, staring at the sky, and wondering if we really are alone...and what could happen next."