@misc{indiciae66a536640ac7,
  title = {A method for development of a system of identification for Appalachian coal-bearing rocks},
  author = {J.C. Ferm and G.A. Weisenfluh and G.C. Smith},
  year = {2002},
  doi = {10.1016/s0166-5162(01)00072-6},
  url = {https://pubs.usgs.gov/publication/70024829},
  note = {Source identifier: 70024829}
}