Geologic Factors Causing Roof Instability and Methane Emission Problems
Subtitle: the Lower Kittanning Coalbed, Cambria County, pa.
Contributors: Mcculloch, C.; Deul, M.
Series: Report of investigations (United States. Bureau of Mines) -- 7769
Publisher: s.n
Published: 1973
Place of publication: S.l
Language: eng
Notes: 1