Blasting practices as they affect the roof of coal mines in Ohio, Pennsylvania, and West Virginia

Author:	Geyer, John Nicholas,
Year:	1933
Document Type:	USBI
Issuing Agency:	United States Bureau of Mines,
SUDOC:	I 28.27:6738
Series:	Information Circular / Bureau of Mines ;
Report Number:	6738
Subjects:	Coal mines and mining--Safety measures
	Blasting--Safety measures
Link:	https://hdl.handle.net/2027/mdp.39015077572330