1. A. L. Robinson,Science 187 (1975) 1185.
2. Idem, ibid. 188 (1975) 40.
3. R. N. Katz,ibid. 208 (1980) 841.
4. A. F. McLean,Amer. Ceram. Soc. Bull. 61 (1982) 861.
5. D. F. Godfrey, ?The Use of Ceramics for Engines?, p. 27 in Science of Ceramics 12, edited by P. Vincenzini, (Ceramurgica s.r.l., Faenza, Italy, 1984).