@misc{indiciae62577bdc4f5f,
  title = {Geology of the Northgate fluorspar district, Colorado},
  author = {T. A. Steven},
  year = {1954},
  doi = {10.3133/mf13},
  url = {https://pubs.usgs.gov/publication/mf13},
  note = {Source identifier: mf13}
}