@misc{indiciae97c875a6ba7f,
  title = {Geologic map of the Hellier quadrangle, Kentucky-Virginia and part of the Clintwood quadrangle, Pike County, Kentucky},
  author = {Donald Clayton Alvord},
  year = {1971},
  doi = {10.3133/gq950},
  url = {https://pubs.usgs.gov/publication/gq950},
  note = {Source identifier: gq950}
}