An efficient UFO investigation was begun in 1947
Its purpose was to see if UFOs post a security risk
The operation was named Project Sign
Project 47, Project Blue Book
Project Blue Book
Blue Book [2x]
Project 47
The following investigation was begun by US Air Force in 1947
Purpose was to see if UFOs post a security risk
The operation was named Project Sign, in 1949 it became Project Grudge
And in 1952 it was renamed yet again to become Project Blue Book
Project Sign
Project 47
Project Blue Book
Its purpose was to see if UFOs post a security risk
Project Blue Book [2x]
Blue Book [2x]
Project Blue Book (Book [?x])
Blue Book (Book [?x])
Project Sign
Project 47
Project Blue Book
Its purpose was to see if UFOs post a security risk