When I was a little girl growing up in the D.C. suburbs, my dad and his friends would sit around late at night in the summer, drinking martinis and gin and tonics, and talking about their work.
One of my dad's friends, George Hoover, was studying UFOs. He'd given my dad a copy of a report called "The Blue Book," which I found in a box of files and enjoyed reading. The Blue Book was a photocopy of a book about UFOs that had been annotated. Apparently George and other folks suspected that the annotations were written by aliens commenting on the validity of various passages in the book.
It made for fascinating reading! One evening George, who was also investigating ESP and psychic phenomena, told my dad that the next time he visited us, he was going to walk right through the wall of our new family room. "I wouldn't do that," my dad said. "That's where I put all the wiring."
My folks have moved several times since Virginia, and I suspect my mom dumped the Blue Book somewhere along the way. This page on About.com has a summary of the Blue Book project that is very much the way I remember hearing about it during the 1960s.