Economic benefits of systematic roof bolting in Ziegler No. 3 Mine, Bell & Zoller Coal & Mining Co., Williamson County, Ill., / by L.W. Kelly.
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Format: | Government Document Book |
Language: | English |
Published: |
[Washington, D.C.] :
U.S. Dept. of the Interior, Bureau of Mines,
1952.
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Series: | Information circular (United States. Bureau of Mines) ;
7633. |
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