@misc{indiciae0570085b6fd3,
  title = {Mineral resources of the United States, 1918: Part II - Nonmetals},
  author = {Gerald Francis Loughlin and Ralph Walter Stone},
  year = {1921},
  doi = {10.3133/70175826},
  url = {https://pubs.usgs.gov/publication/70175826},
  note = {Source identifier: 70175826}
}