@misc{indiciae295b83ba56c0,
  title = {Geologic map of the North Middletown quadrangle, east-central Kentucky},
  author = {Charles T. Helfrich},
  year = {1977},
  doi = {10.3133/gq1444},
  url = {https://pubs.usgs.gov/publication/gq1444},
  note = {Source identifier: gq1444}
}