TY  - RPRT
TI  - Map showing depths to the Pittsburgh coal bed, mining activity, and related surface subsidence, Allegheny, Washington, and Westmoreland Counties, Pennsylvania
AU  - K.O. Bushnell
PY  - 1975
DO  - 10.3133/mf693a
UR  - https://pubs.usgs.gov/publication/mf693A
ID  - mf693A
ER  -