Mine Safety Board decision 29 :doors for controlling ventilation in coal mines

Year:	1938
Document Type:	USBI
Issuing Agency:	U.S. Dept. of the Interior, Bureau of Mines,
SUDOC:	I 28.27:7018
Series:	Information circular / Bureau of Mines ;
Report Number:	7018
Subjects:	Coal mines and mining--Safety measures
	Mine ventilation
Link:	https://hdl.handle.net/2027/mdp.39015077575804