@misc{indiciae939afc696930,
  title = {Phosphate rock resources of the United States},
  author = {James Bachelder Cathcart and Richard Porter Sheldon and Robert A. Gulbrandsen},
  year = {1984},
  doi = {10.3133/cir888},
  url = {https://pubs.usgs.gov/publication/cir888},
  note = {Source identifier: cir888}
}