1. A. E. Owen, pg. 77 in Progress in Ceramic Science, Vol. 3, Ed. J. Burke, Pergamon Press, N.Y. (1963).
2. J. D. Mackenzie, pg. 126 in Modern Aspects of the Vitreous State, Vol. 3, Ed. J. D. Mackenzie, Butterworths, Washington (1964).
3. A. D. Pearson, Ibid, pg. 29.
4. G. W. Morey, The Properties of Glass 2nd ed., Reinhold Publishing Corp., New York (1954).
5. M. B. Volf, Technical Glasses, Putnam and Sons, Ltd., London (1961).