@misc{indiciae0b2fead25c30,
  title = {Preliminary Digital Geologic Map of the Santa Ana 30' x 60' Quadrangle, Southern California},
  author = {D. M. Morton and Kelly R. digital preparation by Bovard and Rachel M. Alvarez},
  year = {2004},
  doi = {10.3133/ofr99172},
  url = {https://pubs.usgs.gov/publication/ofr99172},
  note = {Source identifier: ofr99172}
}