@misc{indiciae44461ccfd422,
  title = {Twenty-First Annual report of the Director of the United States Geological Survey, 1899-1900: Part VI(continued)- Mineral Resources of the United States, 1899 Nonmetallic Products, Except Coal and Coke},
  author = {Charles D. Walcott},
  year = {1901},
  doi = {10.3133/ar21\_6continued},
  url = {https://pubs.usgs.gov/publication/ar21\_6continued},
  note = {Source identifier: ar21\_6continued}
}