@misc{indiciae463a10447bf9,
  title = {Geologic map of the Caledonia quadrangle, Trigg and Christian Counties, Kentucky},
  author = {George E. Ulrich and Harry Klemic},
  year = {1966},
  doi = {10.3133/gq604},
  url = {https://pubs.usgs.gov/publication/gq604},
  note = {Source identifier: gq604}
}