TY  - RPRT
TI  - Map showing depths to the Upper Freeport coal bed, mining activity, and related surface subsidence, and the Redstone coal bed mines, Allegheny, Washington, and Westmoreland Counties, Pennsylvania
AU  - K.O. Bushnell
AU  - J.R. Peak
PY  - 1975
DO  - 10.3133/mf693b
UR  - https://pubs.usgs.gov/publication/mf693B
ID  - mf693B
ER  -