1. Knoop, F., Peters, C. G., and Emerson, W. B., J. Res. Nat. Bur. Stand., 23, 39 (1939).
2. Knoop, F., and Peters, C. G., cited in Ind. Diamond Rev., 5, 103 (1945).
3. Bernhardt, E. O., Z. Metallkunde, 33, 134 (1941).
4. Kruschov, M. M., and Berkovich, E. S., Ind. Diamond Rev., 11, 42 (1951).
5. Wilks, E. M., and Wilks, J., Physical Properties of Diamond (edit. by Berman, R.), 236 (Clarendon, 1965).