@misc{indiciaecf2cd0ebc97e,
  title = {Pyrophyllite, and kyanite and related minerals in the United States, exclusive of Alaska and Hawaii},
  author = {Gilbert H. Espenshade},
  year = {1962},
  doi = {10.3133/mr18},
  url = {https://pubs.usgs.gov/publication/mr18},
  note = {Source identifier: mr18}
}