@misc{indiciae1b40964c8789,
  title = {Geologic map and sections of the Helen quicksilver mine, Mayacmas district, Lake County, California},
  author = {Lowell S. Hilpert and James B. Cathcart},
  year = {1943},
  doi = {10.3133/ofr4382},
  url = {https://pubs.usgs.gov/publication/ofr4382},
  note = {Source identifier: ofr4382}
}