@misc{indiciaec35bd88c5c7b,
  title = {Mine maps of Boulder tungsten district, Colorado},
  author = {Thomas Seward Lovering and Ogden L. Tweto},
  year = {1950},
  doi = {10.3133/ofr5041},
  url = {https://pubs.usgs.gov/publication/ofr5041},
  note = {Source identifier: ofr5041}
}