@misc{indiciaed369e1be8379,
  title = {Jointing in outcropping rocks of Pennsylvanian age, central Greater Pittsburgh region, Pennsylvania},
  author = {William R. Kohl},
  year = {1980},
  doi = {10.3133/ofr8023},
  url = {https://pubs.usgs.gov/publication/ofr8023},
  note = {Source identifier: ofr8023}
}