@misc{indiciaefebe41a0edac,
  title = {Gold deposits along the Rio Madera, northern Bolivia},
  author = {G. E. McKelvey},
  year = {1991},
  doi = {10.3133/ofr91260},
  url = {https://pubs.usgs.gov/publication/ofr91260},
  note = {Source identifier: ofr91260}
}