@misc{indiciaeb90131eeaa40,
  title = {Stratigraphic framework of Cambrian and Ordovician rocks in the central Appalachian Basin from Campbell County Kentucky, to Tazwell County, Virginia},
  author = {Robert T. Ryder and John E. Repetski and Anita G. Harris},
  year = {1997},
  doi = {10.3133/i2530},
  url = {https://pubs.usgs.gov/publication/i2530},
  note = {Source identifier: i2530}
}