@misc{indiciae0036234f84af,
  title = {Geologic map of the Blackey 7 1/2-minute Quadrangle, Knott and Letcher counties, Kentucky},
  author = {Henry A. Waldrop},
  year = {1976},
  doi = {10.3133/ofr76234},
  url = {https://pubs.usgs.gov/publication/ofr76234},
  note = {Source identifier: ofr76234}
}