@misc{indiciae51850f0f13bb,
  title = {Preliminary geologic map of the John Day quadrangle, Oregon},
  author = {T. P. Thayer},
  year = {1956},
  doi = {10.3133/mf51},
  url = {https://pubs.usgs.gov/publication/mf51},
  note = {Source identifier: mf51}
}