@misc{indiciae082a76690ba0,
  title = {Seven maps of the Bully Hill mine, Shasta County, California},
  author = {J. F. Robertson},
  year = {1956},
  doi = {10.3133/ofr56102},
  url = {https://pubs.usgs.gov/publication/ofr56102},
  note = {Source identifier: ofr56102}
}