@misc{indiciaee0ab11fd7e1d,
  title = {Geology of the Columbia quadrangle, Kentucky},
  author = {Richard Q. Lewis and Robert E. Thaden},
  year = {1963},
  doi = {10.3133/gq249},
  url = {https://pubs.usgs.gov/publication/gq249},
  note = {Source identifier: gq249}
}