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Sinking large-diameter drill holes, Lake Superior district underground iron mines
Support of ground, iron-ore mines, Lake Superior district
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Published Year
1940-1949 (2)
Subject
Iron mines and mining--Lake States (2) *
Ground control (Mining)--Lake States (1)
Shaft sinking (1)
Author
Cash, Frank E. (2)
Johnson, Ernest W. (1)
Petersen, Max S. (1)
