@misc{indiciaee3a5e9d8f423,
  title = {Sedimentary phosphate resources classification system of the U.S. Bureau of Mines and the U.S. Geological Survey},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1982},
  doi = {10.3133/cir882},
  url = {https://pubs.usgs.gov/publication/cir882},
  note = {Source identifier: cir882}
}