@misc{indiciae531393d39dcc,
  title = {Geologic map of the Smith Mills Quadrangle, Henderson and Union counties, Kentucky},
  author = {W.D. Johnson and R. L. Norris},
  year = {1974},
  doi = {10.3133/ofr74245},
  url = {https://pubs.usgs.gov/publication/ofr74245},
  note = {Source identifier: ofr74245}
}