@misc{indiciaec7cb1051f501,
  title = {Geologic map of the Olaton quadrangle, western Kentucky},
  author = {William D. Johnson and Avery E. Smith},
  year = {1968},
  doi = {10.3133/gq687},
  url = {https://pubs.usgs.gov/publication/gq687},
  note = {Source identifier: gq687}
}