1. G. A. Rankin andF. E. Wright Amer. J. Sci. 39 (1915) 1.
2. R. W. Nurse, J. H. Welch, andA. J. Majumdar Trans. Brit. Ceram. Soc. 64 (1965) 409.
3. J. K. Leary Nature 194 (482) (1962) 79.
4. T. I. Litvinova andT. F. Raichenko J. Appl. Chem. (USSR) 41 (1968) 61.
5. W. Gutt andJ. Jeevaratnam 1963 quoted by T. D. Robson. Proceedings of the 5th symposium on the chemistry of cement Vol. 1, p. 349.