@misc{indiciae30e061fd07e1,
  title = {Geologic map of the northern and western flanks of the Black Hills, Wyoming and Montana},
  author = {Charles Sherwood Robinson and William Jameson Mapel and Maximilian Hilmar Bergendahl},
  year = {1955},
  doi = {10.3133/tem873},
  url = {https://pubs.usgs.gov/publication/tem873},
  note = {Source identifier: tem873}
}