@misc{indiciae10fc326a4535,
  title = {Geologic map and cross section of the Abra Quadrangle, Costa Rica},
  author = {Rolando M. Castillo and R.D. Krushensky},
  year = {1977},
  doi = {10.3133/i992},
  url = {https://pubs.usgs.gov/publication/i992},
  note = {Source identifier: i992}
}