1. J. E. Ricci, The Phase Rule and Heterogeneous Equilibrium, Van Nostrand, New York (1951).
2. G. W. Morey, Properties of Glass, American Chemical Society Monograph, Reinhold, New York (1954).
3. K. J. Shaver and J. G. Stites, The Heteropolymeric System, Na2O-P205–SO3, 131st National Meeting ACS (April 1957).
4. A. Schleede, W. Schmidt, and H. Kindt, Z. Elektrochem. 38, 633 (1932).
5. E. Thilo and L. Kolditz, Z. Anorg. Allg. Chem. 278, 122 (1955).