1. Hinds K, Gregory JR: National Diet and Nutrition Survey: Children Aged 11/2 to 41/2 Years. Volume 2: Report of the Dental Survey. London, HMSO, 1995.
2. Johnson NW: Introduction: The nature of dental caries; in Johnson NW (ed): Dental Caries: Markers of High and Low Risk Groups and Individuals. Cambridge, Cambridge University Press, 1991, pp 1-12.