@misc{indiciaefbb2642de6c5,
  title = {Fresh-water mollusks of Cretaceous age from Montana and Wyoming},
  author = {Teng-Chien Yen},
  year = {1951},
  doi = {10.3133/pp233a},
  url = {https://pubs.usgs.gov/publication/pp233A},
  note = {Source identifier: pp233A}
}