@misc{indiciae56f830146dbe,
  title = {Generalized correlation chart for the Pennsylvanian of eastern Kentucky showing the principle coal beds, and named sandstones, marine markers, and clay beds},
  author = {Charles L. Rice},
  year = {1977},
  doi = {10.3133/ofr77876},
  url = {https://pubs.usgs.gov/publication/ofr77876},
  note = {Source identifier: ofr77876}
}