@misc{indiciaec6ed8eddba02,
  title = {Field compilation map of the geology of the Keystone area, Black Hills, South Dakota},
  author = {James Jennings Norton},
  year = {1976},
  doi = {10.3133/ofr76297},
  url = {https://pubs.usgs.gov/publication/ofr76297},
  note = {Source identifier: ofr76297}
}