"In response to a Freedom of Information Act request by researcher Michael Ravnitzky, the Air Force Historical Research Agency - which maintains one of the largest repositories of US military historical documents - released in early 2001 a list of its still-classified and still-restricted documents. This unprecedented database contains information on well over half a million documents held by the agency. The 550,000+ documents are identified by call numbers, title, date, author, etc.; they include reports, memos, directives, histories, daily operations reports, oral histories, interviews, situation reports, intelligence summaries, speeches, chronologies, logs, minutes, briefings, correspondence, press clippings, newsletters, photos, slides, audiotapes, and more. We have spotted documents that date back to the 1920s and some as recent as the early 1990s."