@misc{indiciae8917adf5eaa6,
  title = {Composition and properties of the Pierre Shale and equivalent rocks, northern Great Plains region},
  author = {Leonard Gene Schultz and H. A. Tourtelot and J. R. Gill and J.G. Boerngen},
  year = {1980},
  doi = {10.3133/pp1064b},
  url = {https://pubs.usgs.gov/publication/pp1064B},
  note = {Source identifier: pp1064B}
}