Longwall retreat of gate road pillars

Author:	Listak, Jeffrey M.
Additional Authors:	Bauer, Eric R.
Year:	1993
Document Type:	BMRA
Issuing Agency:	U.S. Dept. of the Interior, Bureau of Mines,
SUDOC:	I 28.23:7444
Series:	Report of investigations / Bureau of Mines ;
Report Number:	9444
Subjects:	Pillaring (Mining)
	Longwall mining--Pennsylvania
	Gate roads (Mining)--Pennsylvania
	Ground control (Mining)--Pennsylvania
Links:	https://hdl.handle.net/2027/mdp.39015077558867
	no.9444 1993