wwkirk
Divine
Most of them are fairly old. I guess the author is aiming for classics.
The Five UFO Books Every SETI Advocate Should Read
The Report on Unidentified Flying Objects by Edward J Ruppelt
The UFO Experience: A Scientific Inquiry by J Allen Hynek
The UFO Handbook: A Guide to Investigating, Evaluating, and Reporting UFO Sightings by Allan Hendry
Watch the Skies: A Chronicle of the Flying Saucer Myth by Curtis Peebles
The UFO Phenomena by Edward Ashpole
The Five UFO Books Every SETI Advocate Should Read
The Report on Unidentified Flying Objects by Edward J Ruppelt
The UFO Experience: A Scientific Inquiry by J Allen Hynek
The UFO Handbook: A Guide to Investigating, Evaluating, and Reporting UFO Sightings by Allan Hendry
Watch the Skies: A Chronicle of the Flying Saucer Myth by Curtis Peebles
The UFO Phenomena by Edward Ashpole