1. Kopal, Zdenek, An Introduction to the Study of the Moon (D. Reidel Publishing Company, Dordrecht, Holland, 1966).
2. Muller, P. M., and Sjogren, W. L., Science, 161, 680 (1968).
3. Michael, W. A., Fourteenth General Assembly of the International Union of Geodesy and Geophysics Meeting, Lucerne, Switzerland (1967).
4. Lunar Sample Analysis Planning Team, Science, 167, 449 (1970).
5. Lunar Sample Preliminary Examination Team, Science, 167, 1325 (1970).