@misc{indiciaef61bee1ced0e,
  title = {Natural gamma aeroradioactivity map of the Gaithersburg and part of the Sandy Spring quadrangles, Montgomery County, Maryland},
  author = {Jean Blanchett and Andrew Griscom and F. C. Smith},
  year = {1966},
  doi = {10.3133/gp566},
  url = {https://pubs.usgs.gov/publication/gp566},
  note = {Source identifier: gp566}
}