@misc{indiciae6e741f4773ab,
  title = {Geologic map of the Big Creek Quadrangle, southeastern Kentucky},
  author = {Richard Quintin Lewis and Dan E. Hansen},
  year = {1977},
  doi = {10.3133/ofr77879},
  url = {https://pubs.usgs.gov/publication/ofr77879},
  note = {Source identifier: ofr77879}
}