@misc{indiciaed06e394836a2,
  title = {Bentonite deposits of the northern Black Hills district, Wyoming, Montana, and South Dakota},
  author = {Maxwell M. Knechtel and Sam H. Patterson},
  year = {1962},
  doi = {10.3133/b1082m},
  url = {https://pubs.usgs.gov/publication/b1082M},
  note = {Source identifier: b1082M}
}