@misc{indiciae1629e8d6fd53,
  title = {Terrestrial radioactivity and gamma-ray exposure in the United States and Canada},
  author = {Joseph S. Duval and John M. Carson and Peter B. Holman and Arthur G. Darnley},
  year = {2005},
  doi = {10.3133/ofr20051413},
  url = {https://pubs.usgs.gov/publication/ofr20051413},
  note = {Source identifier: ofr20051413}
}