1. Baker, C.H. (1955). Personal Communication.
2. Annual Report of the Chief Inspector of Factories, W.C.2., H.M. Stationery Office, Kingsway, London, 1954
3. ‘The Twenty Dials Test under Quiet Conditions’, Med. Res. Council A.P.U. Report, 130/50, 1950
4. Broadbent, D.E.: Neglect of the Surroundings in relation to Fatigue Decrement in Output, (H. K. Lewis & Co. Ltd., London 1953a), p. 173–178 Chap. on Fatigue