@misc{indiciae5259b250eb43,
  title = {Twenty-First Annual report of the Director of the United States Geological Survey, 1899-1900: Part III - General geology. Ore and phosphate deposits, Philippines},
  author = {Charles D. Walcott},
  year = {1901},
  doi = {10.3133/ar21\_3},
  url = {https://pubs.usgs.gov/publication/ar21\_3},
  note = {Source identifier: ar21\_3}
}