@misc{indiciae42311d8cd82b,
  title = {Geologic map of the Salem 1 degree by 2 degrees Quadrangle, western Oregon},
  author = {G. W. Walker and R.A. Duncan},
  year = {1989},
  doi = {10.3133/i1893},
  url = {https://pubs.usgs.gov/publication/i1893},
  note = {Source identifier: i1893}
}