Notes
- Andrew , Christopher . 1985 . Secret Service. The Making of the British Intelligence Community 138 – 39 . London
- Beesly , Patrick . 1982 . Room 40, British Naval Intelligence, 1914–1918 London
- Andrew . Secret Service 135 – 45 .
- French , David . 1984 . ‘Sir John French's Secret Service on the Western Front, 1914–15’ . Journal of’ Strategic Studies , 7 ( 4 ) December
- Friedman , William . 1977 . Solving German Codes in World War One Laguna Hills, CA
- Gill , E. W. B. 1934 . War, Wireless and Wangles 22 – 6 . Oxford
- Barker , Wayne G. , ed. 1979 . The History of Codes and Ciphers in the United States During World War One Laguna Hills, CA
- Friedman . German Codes 92
- War Office . 1922 . Statistics of the Military Effort of the British Empire During the Great War, 1914–1920 169 171 – 2 . London
- Beresford , Major C. F. 1887 . ‘Tactics as Affected by Field Telegraphy’ . Journal of the Royal United Service Institute , 31 : 591
- Charteris , John . 1931 . At G.H.Q 28 46 50 55 London
- Marshal‐Cornwall , James . 1984 . Wars and Rumours of Wars 25 London
- Beesly . Room 40 18
- Friedman . German Codes 126
- Barker , ed. Codes and Ciphers 215
- Gill . Wangles 19 – 26 .
- Gill . Wangles 19 – 26 .