@misc{indiciaed4937de03926,
  title = {Geologic map of the El Yunque Quadrangle, Puerto Rico},
  author = {V.M. Seiders},
  year = {1971},
  doi = {10.3133/i658},
  url = {https://pubs.usgs.gov/publication/i658},
  note = {Source identifier: i658}
}