@misc{indiciae73ef818376b1,
  title = {Geologic map of the Smith Mills quadrangle, Henderson and Union Counties, Kentucky},
  author = {William D. Johnson and Ronald Lee Norris},
  year = {1974},
  doi = {10.3133/gq1215},
  url = {https://pubs.usgs.gov/publication/gq1215},
  note = {Source identifier: gq1215}
}