Longwall gate road roof instability and methods of control in the lower Kittanning Coalbed of Central Pennsylvania microform / by E.R. Bauer, J.M. Listak, and E.D. Krupa (Information circular ; 9331)
Longwall gate road roof instability and methods of control in the lower Kittanning Coalbed of Central Pennsylvania microform / by E.R. Bauer, J.M. Listak, and E.D. Krupa