@misc{indiciae1d3f37e7d7fc,
  title = {Potassium, uranium, and thorium maps of the conterminous United States},
  author = {J. S. Duval and F. E. Riggle and J. A. Pitkin and W. J. Jones},
  year = {1995},
  doi = {10.3133/gp1010},
  url = {https://pubs.usgs.gov/publication/gp1010},
  note = {Source identifier: gp1010}
}