1. Sukheswala, R. N., and Udas, G. R., Science and Culture, 29, 563 (1963).
2. Deans, T., Snelling, N. J., and Rapson, J. E., Nature, 210, 290 (1966).
3. Powell, J. L., and DeLong, S. E., Science, 153, 1239 (1966).
4. Subramaniam, A. P., and Parimoo, M. L., Nature, 198, 563 (1963).
5. Subramaniam, A. P., and Parimoo, M. L., Krishnan Volume, 441 (Indian Geophys. Union, 1964).