1. Chase, S. W., Anat. Rec., 36, 239 (1927).
2. Gottlich, B., Dental Caries, chapter 1 (Lea and Febiger, 1947).
3. Orban, B., Oral Histology and Embryology, chapters 3, 4 and 5 (C. V. Mosby and Co., 1949).
4. Noyes, F. B., Schour, I., and Noyes, H. J., Dental Histology and Embryology, chapter 5 (Lea and Febiger, 1938).
5. Stack, M. V., and Fearnhead, R. W., Tooth Enamel, 200 (John Wright and Sons Ltd., 1965).