References
- 'The Guy Liddell Diaries: Vol. I: 1939-1942', ed. by Nigel West (Routledge, London, 2005)
- 'British Intelligence in the Second World War, Volume 4' by F.H. Hinsley and C.A.G. Simkins (HMSO, London, 1990)
- 'Camp 020: MI5 and the Nazi Spies' introduction by Oliver Hoare (Public Record Office, London, 2000)
Read more about this topic: Willem Ter Braak