@misc{indiciaef23d1c3541af,
  title = {Molybdenite near Ramona, San Diego County, California},
  author = {F. C. Calkins},
  year = {1917},
  doi = {10.3133/b640d},
  url = {https://pubs.usgs.gov/publication/b640D},
  note = {Source identifier: b640D}
}