@misc{indiciae47ec4c1bebc1,
  title = {Map showing localities and amounts of metallic mineral production in Colorado},
  author = {William R. Marsh and Roberta W. Queen},
  year = {1973},
  doi = {10.3133/ofr73178},
  url = {https://pubs.usgs.gov/publication/ofr73178},
  note = {Source identifier: ofr73178}
}