@misc{indiciae295eb44d91f2,
  title = {Nitrate deposits of the United States},
  author = {George Rogers Mansfield and Leona Boardman},
  year = {1932},
  doi = {10.3133/b838},
  url = {https://pubs.usgs.gov/publication/b838},
  note = {Source identifier: b838}
}