@misc{indiciaedec895e41a3b,
  title = {Mixed-layer clay in the Pierre Shale and equivalent rocks, northern Great Plains region},
  author = {Leonard Gene Schultz},
  year = {1978},
  doi = {10.3133/pp1064a},
  url = {https://pubs.usgs.gov/publication/pp1064A},
  note = {Source identifier: pp1064A}
}