@misc{indiciaecbbe10ca2855,
  title = {Joint patterns in coal, black shale, gray shale and mudrock, and limestone and dolomite in the Appalachian Basin},
  author = {George Willis Colton and W. J. Perry and Jean D. MacKenzie},
  year = {1981},
  doi = {10.3133/ofr81837},
  url = {https://pubs.usgs.gov/publication/ofr81837},
  note = {Source identifier: ofr81837}
}