References
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- Barker, Wayne G., ed. The History of Codes and Ciphers in the United States During World War I. Laguna Hills: Aegean Park Press, 1979.
- Beesly, Patrick. Room 40: British Naval Intelligence 1914–1918. London: Hamish Hamilton, 1982.
- Devlin, Patrick. Too Proud to Fight: Woodrow Wilson’s Neutrality. London: Oxford University Press, 1974.
- Ferris, John. “Before ‘Room 40’: The British Empire and Signals Intelligence, 1898–1914.” Journal of Strategic Studies 12, no. 4 (1989): 431–457.10.1080/01402398908437390
- Ferris, John. “The Road to Bletchley Park: The British Experience with Signals Intelligence, 1892–1945.” Intelligence and National Security 17, no. 1 (2002): 53–84.10.1080/02684520412331306410
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- Headrick, Daniel. The Invisible Weapon: Telecommunications and International Politics, 1851–1945. Oxford: Oxford University Press, 1991.
- Hiley, Nicholas. “The Strategic Origins of Room 40.” Intelligence and National Security 2, no. 2 (1987): 245–273.10.1080/02684528708431889
- Lambert, Nicholas. Planning Armageddon: British Economic Warfare and the First World War. Cambridge: Harvard University Press, 2012.10.4159/harvard.9780674063068
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- Larsen, Daniel. “Intelligence in the First World War: The State of the Field.” Intelligence and National Security 29, no. 2 (2014): 282–302.10.1080/02684527.2012.727070
- Larsen, Daniel. “War Pessimism in Britain and an American Peace in Early 1916.” The International History Review 34, no. 4 (2012): 795–817.10.1080/07075332.2012.702675
- Link, Arthur, ed. The Papers of Woodrow Wilson. Princeton: Princeton University Press, 1966–1994.
- Link, Arthur. Wilson: The Struggle for Neutrality 1914–1915. Princeton: Princeton University Press, 1960.
- Neu, Charles. Colonel House: A Biography of Woodrow Wilson’s Silent Partner. Oxford: Oxford University Press, 2015.
- U.S. State Department. Papers Relating to the Foreign Relations of the United States, 1915 Supplement: The World War. Washington, DC: Government Printing Office, 1928 [ FRUS 1915].
- U.S. State Department. Papers Relating to the Foreign Relations of the United States, 1916 Supplement: The World War. Washington, DC: Government Printing Office, 1929 [FRUS 1916].
- Weber, Ralph E. “State Department Cryptographic Security, Herbert O. Yardley, & President Woodrow Wilson’s Secret Code.” In In the Name of Intelligence: Essays in Honor of Walter Pforzheimer, edited by Hayden B. Peake and Samuel Halpern, 555–570. Washington, DC: NIBC Press, 1994.
- Weber, Ralph E. United States Diplomatic Codes and Ciphers 1775–1938. Chicago, IL: Precedent, 1979.
- Winkler, Jonathan. “Information Warfare in World War I.” The Journal of Military History 73, no. 3 (2009): 845–867.10.1353/jmh.0.0324
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- Wrixon, Fred B., and Ciphers Codes. Secrets and Cryptic Communication: Making and Breaking Secret Messages from Hieroglyphs to the Internet. New York: Black Dog & Leventhal, 1998.
Archival records
- Churchill College Cambridge Archive Centre (CCAC): Hall Papers.
- Georgetown University Lauinger Library Special Collections (GULL).
- The National Archives (UK) (TNA): Series ADM 137, 223, HW 7, WO 106.
- National Archives Canada (NAC): Record Group 25 f8.
- The National Army Museum (UK) (NAM): Esher Papers.
- The U.S. National Archives and Records Administration (NARA): Record Group 59.
- Yale University Library (YUL): House Papers.