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2. Lunar surface mechanical properties-Surveyor 1;Christensen;J. Geophys. Res.,1967
3. Lunar surface mechanical properties at the landing site of Surveyor 3;Christensen;J. Geophys. Res.,1968
4. Lunar surface mechanical properties;Christensen;J. Geophys. Res.,1968
5. Christensen , E. M. S. A. Batterson H. E. Benson R. Choate R. E. Hutton L. D. Jaffe R. H. Jones H. Y. Ko F. N. Schmidt R. F. Scott R. L. Spencer F. B. Sperling G. H. Sutton Lunar surface mechanical properties Surveyor 6 Mission Report, Part 2, Science Results 47 108 Pasadena, Calif. 1968