1. Recent Estimates of the Abundance of Elements in the Earths Crust;Fleischer;US Geol. Survey Circ.,1953
2. Principles of Geochemistry;Mason,1966
3. Essentiality and Function of Fluoride;Messer,1974
4. Fluoride, Teeth and Health;Clarke,1976
5. Drinking Water and Health;Safe Drinking Water Committee,1977