Roof bolting in the United States

Author:	Thomas, Edward.
Year:	1950
Document Type:	USBI
Issuing Agency:	U.S. Dept. of the Interior, Bureau of Mines,
SUDOC:	I 28.27:7583
Series:	Information circular / Bureau of Mines ;
Report Number:	7583
Subjects:	Coal mines and mining--United States--Safety measures
	Mine roof bolting
Link:	https://hdl.handle.net/2027/mdp.39015078455725