@misc{indiciae4ff369c62766,
  title = {Geology and refractory clay deposits of the Haldeman and Wrigley quadrangles, Kentucky, with a section on coal resources},
  author = {Sam H. Patterson and John W. Hosterman and John Warfield Huddle},
  year = {1962},
  doi = {10.3133/b1122f},
  url = {https://pubs.usgs.gov/publication/b1122F},
  note = {Source identifier: b1122F}
}