@misc{indiciae92cc4d28808f,
  title = {Airborne measurements of terrestrial radioactivity as an aid to geologic mapping},
  author = {James A. Pitkin},
  year = {1968},
  doi = {10.3133/pp516f},
  url = {https://pubs.usgs.gov/publication/pp516F},
  note = {Source identifier: pp516F}
}