U.S. Air Force Academy Text Book:
"... 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!"