@misc{indiciae1ec3ac23765d,
  title = {Soil gas radon compared to aerial and ground gamma-ray measurements at study sites near Greeley and Fort Collins, Colorado},
  author = {J. S. Duval and G.M. Reimer and R.R. Schumann and D.E. Owen and J. K. Otton},
  year = {1990},
  doi = {10.3133/ofr90648},
  url = {https://pubs.usgs.gov/publication/ofr90648},
  note = {Source identifier: ofr90648}
}