@misc{indiciae77fec8ec72cd,
  title = {Natural gamma aeroradioactivity map of the Rockville quadrangle, Montgomery County, Maryland, and Fairfax County, Virginia},
  author = {Jean Blanchett and Andrew Griscom and J. L. Vargo},
  year = {1966},
  doi = {10.3133/gp565},
  url = {https://pubs.usgs.gov/publication/gp565},
  note = {Source identifier: gp565}
}