@misc{indiciae9b1a373de63c,
  title = {Geologic map of the Porcupine Valley quadrangle, Valley County, Montana},
  author = {R. B. Colton},
  year = {1963},
  doi = {10.3133/i368},
  url = {https://pubs.usgs.gov/publication/i368},
  note = {Source identifier: i368}
}