@misc{indiciaeb8b4e5f22009,
  title = {Ammonites and some characteristic bivalves from the Upper Cretaceous Frontier Formation, Natrona County, Wyoming},
  author = {William A. Cobban},
  year = {1990},
  doi = {10.3133/b1917b},
  url = {https://pubs.usgs.gov/publication/b1917B},
  note = {Source identifier: b1917B}
}