@misc{indiciaefec09adda4d5,
  title = {Coking-coal deposits of the western United States},
  author = {Louise R. Berryhill and Paul Averitt},
  year = {1951},
  doi = {10.3133/cir90},
  url = {https://pubs.usgs.gov/publication/cir90},
  note = {Source identifier: cir90}
}