@misc{indiciaeed7df9b3f186,
  title = {Mississippian stratigraphy of northwestern Pennsylvania},
  author = {George R. Schiner and Grant E. Kimmel},
  year = {1972},
  doi = {10.3133/b1331a},
  url = {https://pubs.usgs.gov/publication/b1331A},
  note = {Source identifier: b1331A}
}