Notes
- Lewin , Ronald . 1983 . The American Magic , 197 London : Penguin Books .
- West , Nigel . 1986 . GCHQ, The Secret Wireless War 1900–86 , 222 London : Weidenfeld & Nicolson .
- Welchman , Gordon . 1984 . The Hut Six Story , 130 – 1 . London : Penguin Books .