@misc{indiciae2fdaec6bf010,
  title = {Geologic map of the Monongahela quadrangle, southwestern Pennsylvania},
  author = {John B. Roen and Bion H. Kent and Stanley P. Schweinfurth},
  year = {1968},
  doi = {10.3133/gq743},
  url = {https://pubs.usgs.gov/publication/gq743},
  note = {Source identifier: gq743}
}