@misc{indiciae91cbd6a57d1c,
  title = {Maps of the watersheds of the Santa Margarita and San Luis Rey rivers, Riverside and San Diego counties, California, showing ground-water quality data, 1971},
  author = {G. A. Irwin and F. W. Giessner},
  year = {1971},
  doi = {10.3133/ofr72180},
  url = {https://pubs.usgs.gov/publication/ofr72180},
  note = {Source identifier: ofr72180}
}