@misc{indiciaeaedd02d71f1e,
  title = {Cambrian-Ordovician boundary strata in the central Midcontinent of North America},
  author = {Anthony C. Runkel and J.F. Miller and R.M. McKay and T.H. Shaw and D.J. Basset},
  year = {1999},
  url = {https://pubs.usgs.gov/publication/70021666},
  note = {Source identifier: 70021666}
}