1. Black, G.V.: Operative Dentistry, 9th ed, Milwaukee, Wisconsin: Medico-Dental Publishing Co. , 1955, pp 119-121.
2. Younger, H.B. : Removing the Stain from Mottled Enamel, in Fluorine and Dental Health, Washington, DC: American Association for the Advancement of Science, 1942 , pp 50-53.