@misc{indiciaeae3e80616feb,
  title = {Geologic map of the Trinidad Quadrangle, south-central Colorado},
  author = {R. B. Johnson},
  year = {1969},
  doi = {10.3133/i558},
  url = {https://pubs.usgs.gov/publication/i558},
  note = {Source identifier: i558}
}