1. D. W. Strickler, thesis, Pennsylvania State University (1968).
2. R. Roy, J. Amer. Ceram. Soc. 43 (1960) 670.
3. Idem, ?Symp. on Nucleation and Crystallisation in Glasses and Melts? edited by Reser et al (Amer. Ceram. Soc., 1962) p. 39.
4. W. Vogel and K. Gerth, ibid p. 11.
5. S. M. Ohlberg, H. R. Golob, and D. W. Strickler, ibid p. 55.