@misc{indiciae04cbd50092f4,
  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 = {1997},
  doi = {10.3133/ds19r},
  url = {https://pubs.usgs.gov/publication/ds19R},
  note = {Source identifier: ds19R}
}