@misc{indiciaef0fd7c1745ae,
  title = {Geologic map of the Shady Grove quadrangle, Crittenden and Caldwell Counties, Kentucky},
  author = {Robert Denny Trace and James Edward Palmer},
  year = {1971},
  doi = {10.3133/gq880},
  url = {https://pubs.usgs.gov/publication/gq880},
  note = {Source identifier: gq880}
}