@misc{indiciae4d626b5c9669,
  title = {Preliminary report on the economic geology of Gilpin County, Colorado},
  author = {E.S. Bastin and J. M. Hill},
  year = {1916},
  doi = {10.3133/b620m},
  url = {https://pubs.usgs.gov/publication/b620M},
  note = {Source identifier: b620M}
}