@misc{indiciae49bf307cf1be,
  title = {Geologic map of the Carolina Quadrangle, Puerto Rico},
  author = {W. H. Monroe},
  year = {1977},
  doi = {10.3133/i1054},
  url = {https://pubs.usgs.gov/publication/i1054},
  note = {Source identifier: i1054}
}