@misc{indiciae2685e1da5102,
  title = {Notes on the Unaweep copper district, Colorado},
  author = {B. S. Butler},
  year = {1915},
  doi = {10.3133/b580b},
  url = {https://pubs.usgs.gov/publication/b580B},
  note = {Source identifier: b580B}
}