1. F. F. LANGE,J. Amer. Ceram. Soc. 67 (1984) 83.
2. B. FEGLEY JR, P. WHITE and H. K. BOWEN,Amer. Ceram. Soc. Bull. 64 (1985) 1115.
3. D. W. JOHNSON,Jpn Ceram. Bull. 60 (1981) 221.
4. L. M. SHEPPARD,Mater. Eng. (June 1984) 45.
5. P. K. ILER, in ?Science of Ceramic Chemical Processing?, edited by L. L. Hench and D. R. Ulrich (John Wiley, New York, 1986) p. 3.