1. Carrier, W. D. III, Bromwell, L. G., and Martin, R. T.: 1972,Strength and Compressibility of Returned Lunar Soil, presented to Third Lunar Science Conference, Houston.
2. Cherkasov, I. I. and Shvarev, V. V.: 1968,Zemlya i Vselennaya 2, 15.
3. Christensen, E. M., Batterson, S. A., Benson, H. E., Chandler, C. E., Jones, R. H., Scott, R. F., Shipley, E. N., Sperling, F. B., and Sutton, G. H.: 1967,J. Geophys. Res. 72, 801.
4. Christensen, E. M., Batterson, S. A., Benson, H. E., Choate, R., Jaffe, L. D., Jones, R. H., Ko, H. Y., Spencer, R. L., Sperling, F. B., and Sutton, G. H.: 1968a,J. Geophys. Res. 73, 4081.
5. Christensen, E. M., Batterson, S. A., Benson, H. E., Choate, R., Hutton, R. E., Jaffe, L. D., Jones, R. H., Ko, H. Y., Schmidt, F. N., Scott, R. F., Spencer, R. L., Sperling, F. B., and Sutton, G. H.: 1968b, inSurveyor VI: A Preliminary Report, Special Report 166, 41?95, National Aeronautics and Space Administration, Washington, D. C.