1. Magitot, E., Treatise on Dental Caries. Translated by Thomas H. Chandler ( Cam-bridge, Riverside Press: 1878 ), p. 19.
2. Churchill, H.R., Normal Histology and Histogenosis of the Human Teeth and Associated Parts (Philadelphia, J. B. Lippincott Co. 1935), p. 39.
3. Orban, B., Dental Histology and Embryology (Philadelphia, P. Blakiston's Son & Co. 1929), p. 111.