@misc{indiciae12c229a555fc,
  title = {Geology and resource assessment of Costa Rica at 1:500,000 scale; a digital representation of maps of the U.S. Geological Survey's 1987 Folio I-1865},
  author = {Paul G. Schruben},
  year = {1996},
  doi = {10.3133/ds19},
  url = {https://pubs.usgs.gov/publication/ds19},
  note = {Source identifier: ds19}
}