1. Kyushu Taika-Renga Kabushiki Kaisha, Brit. Pat. 1 533 890, 29 November (1978).
2. C. Taylor's Sons Company, Brit. Pat. 1421 418, 21 January (1976).
3. R. D. Shaw andC. Shaw, Brit. Pat. 1313498, 11 April (1973).
4. R. M. Spriggs andS. T. Bender,J. Amer. Ceram. Soc.
62 (1949) 506J.
5. H. G. Emblem,Tram. J. Brit. Ceram. Soc.
74 (1975) 223.