@misc{indiciae718a728055d9,
  title = {Geologic map and digital database of the Porcupine Wash 7.5 minute Quadrangle, Riverside County, southern California},
  author = {Robert E. Powell},
  year = {2001},
  doi = {10.3133/ofr0130},
  url = {https://pubs.usgs.gov/publication/ofr0130},
  note = {Source identifier: ofr0130}
}