Without any hesitation I would recommend the works of Richard Dolan. He is an Historian who has accumulated the best discussion on the topics. The first book to get is 'UFOs For The Twentieth Century Mind'. This book is an excellent short version of his two volume (so far) compendium of the History of UFOs. He plans a third in the set, which would bring the History up to date from 1991 to the present. His methodology is to report data, such as government documents obtained through FOIA, and the best eyewitness sightings, especially by military personnel at Air Force bases and nuclear missile facilities.
The evidence of something very advanced (wingless airfoils, not rockets) in the skies all over the Earth is no longer in dispute. And based upon the dates of the earliest sightings of very advanced technology, I find it amazing that anyone could doubt that non-terrestrial visitation is a reality.
Richard Dolan. Isn’t he a regular on Coast to Coast?
Kinda limits his legitimacy, doesn’t it?
BTW, the nuns at my grade school would have beaten your knuckles bloody for using “an” before a consonant.
It’s an affectation of the pseudo-intellectual. Just FYI.