@misc{indiciaefbad1f52abf9,
  title = {Energy resources map of the Powder River Basin, Wyoming and Montana},
  author = {W. R. Keefer and P. W. Schmidt},
  year = {1973},
  doi = {10.3133/i847a},
  url = {https://pubs.usgs.gov/publication/i847A},
  note = {Source identifier: i847A}
}