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Factors and conditions that aid in alinement of pillar extraction lines in coal mining
Blasting practices as they affect the roof of coal mines in Ohio, Pennsylvania, and West Virginia
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Published Year
1930-1939 (2) *
Subject
Blasting--Safety measures (1)
Coal mines and mining--Pennsylvania (1)
Coal mines and mining--Safety measures (1)
Mining engineering (1)
Author
Geyer, John Nicholas, (2) *