@misc{indiciaed3e91fb98f33,
  title = {Geologic and coal-bed map of Clarion County, Pennsylvania},
  author = {E. D. Patterson and J. A. Van Lieu},
  year = {1972},
  doi = {10.3133/i715},
  url = {https://pubs.usgs.gov/publication/i715},
  note = {Source identifier: i715}
}