@misc{indiciaee8b7510c5243,
  title = {Twentieth Annual report of the United States Geological Survey, 1898-1899: Part VI (continued) - Mineral Resources of the United States, 1898, Nonmetallic Products, Except Coal and Coke},
  author = {Charles D. Walcott},
  year = {1899},
  doi = {10.3133/ar20\_6continued},
  url = {https://pubs.usgs.gov/publication/ar20\_6continued},
  note = {Source identifier: ar20\_6continued}
}