@misc{indiciaeeb81dd899bea,
  title = {Geology of anthracite in the western part of the Shenandoah quadrangle, Pennsylvania},
  author = {Walter Danilchik and Howard E. Rothrock and Holly Clyde Wagner},
  year = {1955},
  doi = {10.3133/coal21},
  url = {https://pubs.usgs.gov/publication/coal21},
  note = {Source identifier: coal21}
}