@misc{indiciaec1b51b231d0a,
  title = {Structure-contour map of the Olive Hill Clay Bed in northeastern Kentucky},
  author = {John W. Hosterman},
  year = {1963},
  doi = {10.3133/mf261},
  url = {https://pubs.usgs.gov/publication/mf261},
  note = {Source identifier: mf261}
}