@misc{indiciae052a60a0c4c7,
  title = {Helium surveys over known geothermal resource areas in the Imperial Valley, California},
  author = {Alan A. Roberts},
  year = {1975},
  doi = {10.3133/ofr75427},
  url = {https://pubs.usgs.gov/publication/ofr75427},
  note = {Source identifier: ofr75427}
}