@misc{indiciae2a5fc818607e,
  title = {Geologic map of the David quadrangle, eastern Kentucky},
  author = {William F. Outerbridge},
  year = {1968},
  doi = {10.3133/gq720},
  url = {https://pubs.usgs.gov/publication/gq720},
  note = {Source identifier: gq720}
}