1. American Friends Service Committee (1979) The Police Threat to Political Liberty, American Friends Service Committee, Philadelphia, PA.
2. Andrew, C. (1985) Secret Service: The Making of the British Intelligence Community, Heinemann, London.
3. Brenton, M. (1964) The Privacy Invaders, Coward-McCann Inc., New York, NY.
4. Bunyan, T. (1976) The History and Practice of the Political Police in Britain, Julian Friedmann Publishers, London 1976.
5. Caiden, G.E. (1977) Police Revitalisation, Lexington Books, Lexington, MA.