@misc{indiciae0e228c93080c,
  title = {Geologic map of the Ogle Quadrangle, Clay and Knox Counties, Kentucky},
  author = {Russell G. Ping and R.E. Sergeant},
  year = {1977},
  doi = {10.3133/ofr77635},
  url = {https://pubs.usgs.gov/publication/ofr77635},
  note = {Source identifier: ofr77635}
}