. . . . . "Closure of underground copper mines hearing before the Subcommittee on Minerals, Materials, and Fuels of the Committee on Interior and Insular Affairs, United States Senate, Ninety-third Congress, second session, to review the Anaconda Company's plans to close its underground copper mines in Butte, Montana, November 25, 1974"@en . . . . . . . "Closure of underground copper mines"@en . . "Closure of underground copper mines : hearing before the Subcommittee on Minerals, Materials, and Fuels of the Committee on Interior and Insular Affairs, United States Senate, Ninety-third Congress, second session, to review the Anaconda Company's plans to close its underground copper mines in Butte, Montana, November 25, 1974" . . . . . . . . . .