@misc{indiciae48931da3f3c6,
  title = {Geologic map of the Powderhorn quadrangle, Gunnison and Saguache Counties, Colorado},
  author = {David Carl Hedlund and Jerry Chipman Olson},
  year = {1975},
  doi = {10.3133/gq1178},
  url = {https://pubs.usgs.gov/publication/gq1178},
  note = {Source identifier: gq1178}
}