@misc{indiciae144bc7591000,
  title = {The Lexington limestone (Middle Ordovician) of central Kentucky},
  author = {Douglas F. B. Black and Earle Rupert Cressman and William Charles MacQuown},
  year = {1965},
  doi = {10.3133/b1224c},
  url = {https://pubs.usgs.gov/publication/b1224C},
  note = {Source identifier: b1224C}
}