The files were posted by Greenewald to his online database called Black Vault. You can access Greenwald’s Black Vault here.
Greenewald’s Black Vault also includes documents from Project Sign and Project Grudge, which predate Project Blue Book and go back to the 1940s.
From USA Today:
“Project Blue Book was based at Wright-Patterson Air Force Base near Dayton, Ohio. Between 1947 and 1969, the Air Force recorded 12,618 sightings of strange phenomena — 701 of which remain ‘unidentified.’There is nothing of 1947′s infamous Roswell, New Mexico crash in the declassified files. Many conspiracy theorists believe the military retrieved a crashed alien spacecraft and the aliens traveling inside.
“According to a 1985 fact sheet from Wright-Patterson, posted online by the National Archives, the Air Force decided to discontinue UFO investigations after concluding that ‘no UFO reported, investigated and evaluated by the Air Force has ever given any indication of threat to our national security (and) there has been no evidence indicating that sightings categorized as “unidentified” are extraterrestrial vehicles.’”
Though the documents have been available for some time, there’s been no way to easily sift through the 12,600 files. They were previously on microfilm available only at the National Archives in Washington. Black Vault makes them available in downloadable PDF format.