@misc{indiciae054f136986be,
  title = {Coal resources of the Gillette area, Wyoming},
  author = {N.M. Denson and W. R. Keefer and G. H. Horn},
  year = {1973},
  doi = {10.3133/i848c},
  url = {https://pubs.usgs.gov/publication/i848C},
  note = {Source identifier: i848C}
}