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2. Gradients of dentine exposure in human molar tooth attrition
3. Klatsky, M., and Fisher, R.L.: The Human Masticatory Apparatus, Brooklyn: Dental Items of Interest Pub. Co., 1953, p 223.
4. Cole, S.: Races of Man, 2nd ed, London : Trustees of the British Museum (Natural History), 1965, pp 55-124.