J. D. Mulholland, E. C. Silverberg. Measurement of Physical Librations Using Laser Retroreflectors. Earth, Moon, and Planets. 1972, 4 (1-2): 155–159. Bibcode:1972Moon....4..155M. doi:10.1007/BF00562923.
J. D. Mulholland, E. C. Silverberg. Measurement of Physical Librations Using Laser Retroreflectors. Earth, Moon, and Planets. 1972, 4 (1-2): 155–159. Bibcode:1972Moon....4..155M. doi:10.1007/BF00562923.