1. Central Statistical Office (1982?91) Monthly digest of statistics. HMSO, London
2. Chambers JM, Hastie TJ (1992) Statistical models in S. Wadsworth and Brooks, Pacific Grove, California
3. Chief Medical Officer (1990) On the state of the public health for the year 1989. HMSO, London
4. Hobbs BC, Roberts D (1987) Food poisoning and food hygiene. Edward Arnold, London
5. House of Commons Agriculture Committee (1989) First report on salmonella in eggs. HMSO, London