@misc{indiciae64b8288fae93,
  title = {Radon-222 content of natural gas samples from Upper and Middle Devonian sandstone and shale reservoirs in Pennsylvania\—preliminary data},
  author = {E. L. Rowan and T. F. Kraemer},
  year = {2012},
  doi = {10.3133/ofr20121159},
  url = {https://pubs.usgs.gov/publication/ofr20121159},
  note = {Source identifier: ofr20121159}
}