@misc{indiciaeb1f5c85f3b4e,
  title = {Geology of the Calamity Peak area, Custer County, South Dakota},
  author = {Donald Harry Kupfer},
  year = {1963},
  doi = {10.3133/b1142e},
  url = {https://pubs.usgs.gov/publication/b1142E},
  note = {Source identifier: b1142E}
}