@misc{indiciae2493eb77f295,
  title = {Nature and origin of deposits of phosphate of lime},
  author = {Richard Alexander Fullerton Penrose and Nathaniel Southgate Shaler},
  year = {1888},
  doi = {10.3133/b46},
  url = {https://pubs.usgs.gov/publication/b46},
  note = {Source identifier: b46}
}