The Edge of Reality : Two Scientists Evaluate What We Know of the UFO Phenomenon

An Illustrated History of UFOs

UFOs : A Scientist Explains What We Know (And Dont Know)

The Psychology of Public Belief in Unexplained Phenomena : Close Encounters, Extraterrestrials and UFOs

The Invisible College : What A Group Of Scientists Has Discovered About Ufo Influence On The Human Race Jacques Vallee