@misc{indiciae730dad5d0ec5,
  title = {Geologic map of the Utuado quadrangle, Puerto Rico},
  author = {A. E. Nelson},
  year = {1967},
  doi = {10.3133/i480},
  url = {https://pubs.usgs.gov/publication/i480},
  note = {Source identifier: i480}
}