@misc{indiciae2d7313609aad,
  title = {Geology and occurrence of radon},
  author = {R. Randall Schumann and Linda C. Gundersen and A. B. Tanner},
  year = {1994},
  url = {https://pubs.usgs.gov/publication/70209724},
  note = {Source identifier: 70209724}
}