Henkes, William C. Satellite monitoring of open pit mining operations / by William C. Henkes - Washington, D.C. : U.S. Government Printing Office, 1971 - 28 p. ; 26 cm. - Information circurlar ; 8530 . Bureau of mines Subjects--Topical Terms: Artificial SatelliteLunar geologyLunar petrology Dewey Class. No.: 523.391