1. Skinner, E.W., and Phillips, R.W.: The Science of Dental Materials, Philadelphia: W. B. Saunders Co., 1967, pp 343-347, 619-620.
2. Peyton, F.A.: Restorative Dental Materials, S. Louis C. V. Mosby Company , 1964, p 411.
3. Gilmore, H.W.: Textbook of Operative Dentistry, S. Louis C. V. Mosby Company , 1967, pp 356-361.