@misc{indiciae74f6b8a38581,
  title = {Geologic and metallogenic maps of Puerto Rico},
  author = {D. P. Cox and R. P. Briggs},
  year = {1971},
  doi = {10.3133/ofr7178},
  url = {https://pubs.usgs.gov/publication/ofr7178},
  note = {Source identifier: ofr7178}
}