You can access the referenced “Vault” Documents via http://vault.fbi.gov/UFO
Article From The Guardian
FBI destroyed thousands of UFO reports, 1949 memo reveals
By Ian Sample
The FBI was so overwhelmed with sightings of flying saucers in the 1940s that agents routinely destroyed reports because of lack of filing space, according to documents released by the organisation.
The policy is outlined in a memo sent on 16 August 1949 to J Edgar Hoover, the director of the bureau, along with documents on UFOs compiled by agents after statements from witnesses.
The documents are among a batch of papers related to UFO sightings that has been made available through The Vault, the FBI’s online records database.
In one intriguing note, sent on 22 March 1950, special agent Guy Hottel, head of the FBI’s Washington field office, wrote to Hoover with information on three “so-called flying saucers” that a witness claimed had crash-landed in New Mexico.
From The Guardian