@misc{indiciae23ce3301a53e,
  title = {The gold pan as a quantitative geologic tool},
  author = {P. K. Theobald},
  year = {1957},
  doi = {10.3133/b1071a},
  url = {https://pubs.usgs.gov/publication/b1071A},
  note = {Source identifier: b1071A}
}