@misc{indiciae0ff6aa120e2c,
  title = {Geologic map of the Opheim 1° x 30' quadrangle, Valley and Daniels counties, Montana},
  author = {R. B. Colton and S. T. Whitaker and W. C. Ehler},
  year = {1989},
  doi = {10.3133/ofr89319},
  url = {https://pubs.usgs.gov/publication/ofr89319},
  note = {Source identifier: ofr89319}
}