@misc{indiciae9b5ff37624f0,
  title = {Twentieth Annual report of the United States Geological Survey, 1898-1899: Part VI - Mineral resources of the United States 1898, Metallic Products, Coal, and Coke},
  author = {Charles D. Walcott},
  year = {1899},
  doi = {10.3133/ar20\_6},
  url = {https://pubs.usgs.gov/publication/ar20\_6},
  note = {Source identifier: ar20\_6}
}