@misc{indiciae124f80bda8fd,
  title = {Age of biostratigraphic horizons within the Ordovician and Silurian systems},
  author = {Michael J. Kunk and J. Sutter and J. D. Obradovich and Marvin A. Lanphere},
  year = {1985},
  doi = {10.1144/gsl.mem.1985.010.01.10},
  url = {https://pubs.usgs.gov/publication/70207636},
  note = {Source identifier: 70207636}
}