@misc{indiciaec941958b2481,
  title = {Economic geology of Gilpin County and adjacent parts of Clear Creek and Boulder Counties, Colorado},
  author = {E.S. Bastin and J. M. Hill},
  year = {1917},
  doi = {10.3133/pp94},
  url = {https://pubs.usgs.gov/publication/pp94},
  note = {Source identifier: pp94}
}