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3. Grieveson, P., Jack, K. H., and Wild, S., in The Crystal Chemistry of Ceramic Phases in the Silicon-nitrogen-oxygen and Related Systems, Progress Report No. 1, Ministry of Defence Contract N/CP.61/9411/67/4B/M.P. 387, July 1968.
4. Wild, S., Grieveson, P., and Jack, K. H., The Crystal Chemistry of New Metal-silicon-nitrogen Ceramic Phases, Symposium on Special Ceramics, 1970; See Special Ceramics 5 (edit. by Popper, P.), 289 (B.C.R.A., Stoke-on-Trent, July 1970).
5. Hardie, D., and Jack, K. H., Nature, 180, 332 (1957).