@misc{indiciaec8e41462aeff,
  title = {Studies of the Pierre Shale in the Northern Great Plains},
  author = {James R. Gill and William Aubrey Cobban and Leonard Gene Schultz},
  year = {1976},
  doi = {10.3133/pp392},
  url = {https://pubs.usgs.gov/publication/pp392},
  note = {Source identifier: pp392}
}