@misc{indiciae0b57b46586cf,
  title = {Metallogenic map of Puerto Rico},
  author = {Dennis P. Cox and Reginald P. Briggs},
  year = {1973},
  doi = {10.3133/i721},
  url = {https://pubs.usgs.gov/publication/i721},
  note = {Source identifier: i721}
}