Bibliography
- CIA. “Before WWII: A Siloed Approach to Foreign Intelligence.” Accessed January 8, 2023. https://www.cia.gov/legacy/cia-history/
- Jeffreys-Jones, R. In Spies We Trust. Oxford: Oxford University Press, 2013.
- Murray, R. K. The Harding Era. Minneapolis, MN: University of Minnesota Press, 1969.
- Voska, E. V., and W. Irwin. Spy and Counter-Spy. London: George G. Harrap, 1941.