@misc{indiciae7d0cd99e00ed,
  title = {Preliminary geologic map of the Placerville quadrangle, Colorado},
  author = {A.L. Bush and C. S. Bromfield and C. T. Pierson},
  year = {1956},
  doi = {10.3133/tem777},
  url = {https://pubs.usgs.gov/publication/tem777},
  note = {Source identifier: tem777}
}