1. See, for example,E. M. Wilks andJ. Wilks,Industrial Diamond Review 26 (1966) 52.
2. E. M. Wilks andJ. Wilks, Proceedings of the International Industrial Diamond Conference, Oxford, England, Volume One, Ed. John Burls, Industrial Diamond Information Bureau, London (1967) pp. 93?103.
3. Yu Litvin andV. P. Butuzov,Dolakady 181 (1968) 1123.
4. V. I. Shemanin,Geologiya i Geogizika 11 (1966) 116.
5. R. M. Chrenko, H. M. Strong, andR. E. Tuft,Phil. Mag. 23 (1971) 313.