Notes
- Hinsley , F.H. and Stripp , A. , eds. 1993 . Codebreakers , Oxford : OUP .
- West , Nigel . 1987 . GCHQ: The Secret Wireless War 1900—86 , London : Coronet Books, Hodder .
- Taylor , A.J.P. 1965 . English History 1914–1945 , 219ff 225 Oxford : OUP .