@misc{indiciae625df461de82,
  title = {Geologic map of Montana},
  author = {C. P. Ross and D. A. Andrews and I. J. Witkind},
  year = {1955},
  doi = {10.3133/70046740},
  url = {https://pubs.usgs.gov/publication/70046740},
  note = {Source identifier: 70046740}
}