1. Industrial Health Advisotry Committees Sub-Committee on Noise, (1972) The code of practice for reducing the exposure of employed persons to noise, published by HMSO on behalf of Department of Employment.
2. British Occupational Hygiene Society (BOHS) (1971) Hygience Standard for Wide-Band Noise.
3. International Organisation of Standardisation (180) (1971) Assessment of Occupational Noise Exposure for Hearing Conservation Purposes, Recommendation R1999.