@misc{indiciae806716d0f4a8,
  title = {Preliminary stratigraphic cross section showing radioactive black shale zones in the Devonian black shales in eastern Ohio and west-central Pennsylvania},
  author = {John B. Roen and L.G. Wallace and Wallace De Witt},
  year = {1977},
  doi = {10.3133/ofr77840},
  url = {https://pubs.usgs.gov/publication/ofr77840},
  note = {Source identifier: ofr77840}
}