"... the UFO Phenomenon is 50,000 Years Old"
The above statement was found in an official U.S. Air Force Academy text book from the late 1960s:
http://www.youtube.com/watch?v=RkiX4rOxsRs
And here are other statements from the text book:
"... may be four different groups of aliens ..." and
"... the UFO problem ..."
Comment by narrator George Knapp regarding the above statements: "The Air Force's own words!"
