@misc{indiciae7c53dc3fe74b,
  title = {Lower Middle Ordovician stratigraphy of the Shenandoah Valley, Virginia},
  author = {B.N. Cooper and G.A. Cooper},
  year = {1946},
  doi = {10.1130/0016-7606(1946)57[35:lmosot]2.0.co;2},
  url = {https://pubs.usgs.gov/publication/70198516},
  note = {Source identifier: 70198516}
}