@misc{indiciae713e98b8c1bd,
  title = {Grade-tonnage model of hot-spring gold-silver; a supplement to U.S. Geological Survey Bulletin 1693},
  author = {B. R. Berger and D.A. Singer},
  year = {1987},
  doi = {10.3133/ofr87272c},
  url = {https://pubs.usgs.gov/publication/ofr87272C},
  note = {Source identifier: ofr87272C}
}