1. P. W. McMillan, in ?Glass Ceramics? (Academic, London, 1979) p. 223.
2. Z. Strnad, in ?Glass Science and Technology? (Elsevier, Amsterdam, 1986) p. 85.
3. G. Partridge, Glass Technol. 23 (1982) 3.
4. G. H. Beall, in ?Advances in Ceramics?, Vol. 18 (American Ceramic Society, Columbus, Ohio, 1986) p. 157.
5. D. R. Stewart, in ?Advances in Nucleation and Crystallization of Glasses? (American Ceramic Society, Columbus, Ohio, 1971) p. 5.