Barrier Pillars in the Western Middle Field: Anthracite Region of Pennsylvania

Author:	Ash, S. H. (Simon Harry), b. 1889
Additional Authors:	Link, H. B., Kennedy, D. O.
Year:	1953
Document Type:	N/A
Series:	United States Bureau of Mines Reports
Report Number:	Bulletin 521
Link:	https://digital.library.unt.edu/ark:/67531/metadc12681/