@misc{indiciae1ec91e250cd7,
  title = {Coal resources map of Wyoming},
  author = {Henry L. Berryhill and Donald Brown and R.N. Burns and J.X. Combo},
  year = {1951},
  doi = {10.3133/coal6},
  url = {https://pubs.usgs.gov/publication/coal6},
  note = {Source identifier: coal6}
}