@misc{indiciae2a6332a2471f,
  title = {Geologic map of Oregon east of the 121st meridian},
  author = {G. W. Walker},
  year = {1977},
  doi = {10.3133/i902},
  url = {https://pubs.usgs.gov/publication/i902},
  note = {Source identifier: i902}
}