@misc{indiciae2c026eb8ef13,
  title = {Tin-bearing placers near Guadalcazar, State of San Luis Potosi, Mexico},
  author = {Carl Fries and Eduardo Schmitter},
  year = {1948},
  doi = {10.3133/b960d},
  url = {https://pubs.usgs.gov/publication/b960D},
  note = {Source identifier: b960D}
}