Bushnell, K. O. (1975). Map showing depths to the Pittsburgh coal bed, mining activity, and related surface subsidence, Allegheny, Washington, and Westmoreland counties, Pennsylvania. U.S. Geological Survey.
Chicago Style (17th ed.) CitationBushnell, Kent O. Map Showing Depths to the Pittsburgh Coal Bed, Mining Activity, and Related Surface Subsidence, Allegheny, Washington, and Westmoreland Counties, Pennsylvania. [Washington, D.C.]: U.S. Geological Survey, 1975.
MLA (8th ed.) CitationBushnell, Kent O. Map Showing Depths to the Pittsburgh Coal Bed, Mining Activity, and Related Surface Subsidence, Allegheny, Washington, and Westmoreland Counties, Pennsylvania. U.S. Geological Survey, 1975.
Warning: These citations may not always be 100% accurate.