@misc{indiciaec0300edc6423,
  title = {Geologic map of the Madrid quadrangle, western Kentucky},
  author = {William D. Johnson},
  year = {1978},
  doi = {10.3133/gq1482},
  url = {https://pubs.usgs.gov/publication/gq1482},
  note = {Source identifier: gq1482}
}