1. P. W. McMILLAN, “Glass Ceramics”, 2nd Edn (Academic, London, 1979).
2. P. F. JAMES, in “Advanced Ceramics” Vol. 4, edited by J. H. Simmons, D. R. Uhlmann and G. H. Beall (American Ceramic Society, Columbus, Ohio 1982) p. 1.
3. P. F. JAMES,J. Non-Cryst. Solids 73 (1985) 517.
4. Powder Diffraction File, Card Numbers 15-519 (JCPDS, International Centre for Diffraction Data).