1. Baldwin, R. B.: The measure of the moon. University of Chicago Press 1963.
2. Shoemaker, E. M., et al.: Apollo 12 Preliminary Science Report, NASA SP-235, p. 113 (1970).
3. Greeley, R., Gault, D. E.: The Moon2, 10 (1971).
4. Hörz, F., Hartung, J. B., Gault, D. E.: Earth Planet. Sci. Lett.10, 381 (1971).
5. Bloch, M. R., et al.: Proc. Second Lunar Sci. Conf.3, 2639 (1971).