FBI and Majestic 12 documents
In september 1947 american Air Force was formed and at the same date were Majestic 12 aswell, group of 12 people that where leading the secret investigation of fallen crafts of non-human origin. In december of that year "Project Saucer" later known as Project Sign was also formed. Although Jaime Shanderas documents show that "print and paper" were from 1970s Stanton Friedman was convinced they were genuine copy. There are many other documents (some of MJ 12, FBI and other documents) that show cover up was going on.
Majestic 12- please go to page 12!
Black Vault and FBI