@misc{indiciae1c4e3ad417bc,
  title = {Geologic map of the Ponce quadrangle, Puerto Rico},
  author = {R.D. Krushensky},
  year = {1972},
  doi = {10.3133/ofr72214},
  url = {https://pubs.usgs.gov/publication/ofr72214},
  note = {Source identifier: ofr72214}
}