1. Aid, M., ‘Eavesdroppers of the Kremlin: KGB Sigint during the Cold War’, in Leeuw, Karl de and Jan Bergstra (eds), The History of Information Security: A comprehensive handbook (Elsevier: Amsterdam, 2007).
2. Andrew, Christopher, Secret Service: The making of the British intelligence community (Heinemann: London, 1985).
3. Andrew, Christopher and Oleg Gordievsky (eds.), Instructions from the Centre: Top secret files on KGB foreign operations, 1975–85 (Hodder and Stoughton: London, 1991).
4. Andrew, Christopher and Vasili Mitrokhin, The Mitrokhin Archive: The KGB in Europe and the West (Allen Lane Penguin Press: Harmondsworth, 1999). A vast book of great importance; after the first chapters, it is probably best read via the excellent index.
5. Barkin, Noah, ‘Five Eyes intelligence alliance builds coalition to counter China’, Reuters, 12 October 2018 [www].