Archival research for several of these essays involved work in archival repositories in Australia, Japan, and the United States. The essay on Number Fifty-five Wireless Section capitalized on the section's war diary and daily log with appendices available at the Australian War Memorial, Canberra, ACT, Australia. Filed among other operational records, to my knowledge, Number Fifty-five's account is the sole declassified day-by-day account of the actual workings of a signals intercept site, and for that reason its documents are unique. Holdings at the Australian Archives, Dicksen, ACT, shed light on Australian government policy regarding signals intelligence. These documents are complemented by the partially declassified Allied Central Bureau Technical Reports and associated items available at the Australian Archives, Victoria, since the early 1990s. In 1996 the U.S. National Security Agency (NSA) turned over to the U.S. National Archives and Records Administration (SARA) more than 5000 individual files under the title "Historical Crypto- graphic Collection, Pre-World War I-World War II" in Record Group 457. These include a complete and unredacted set of Central Bureau's Technical Reports. These records are now available for researchers at the NARA College Park, Maryland, facility. Also housed at College Park is the remainder of Record Group 457, which contains NSA material released since 1977, much of which appears in essays throughout this collection.
The outstanding collections of public and private papers at the George C. Marshall Library and Archives, Lexington VA, the MacArthur Memorial Bureau of Archives, Norfolk VA, and the U.S. Army Military History Institute,