Recommended safety standards for shaft sinking :1957

Year:	1957
Document Type:	USBI
Issuing Agency:	U.S. Dept. of the Interior, Bureau of Mines,
SUDOC:	I 28.27:7810
Series:	Information circular / United States. Bureau of Mines ;
Report Number:	7810
Subjects:	Coal mines and mining--Safety measures--Standards--United States
	Shaft sinking--Safety measures--Standards--United States
Link:	https://hdl.handle.net/2027/mdp.39015078459859