@misc{indiciaec3e18c7cf807,
  title = {Stratigraphy and petrology of the Permian rocks of southwestern Montana},
  author = {Earle R. Cressman and Roger W. Swanson},
  year = {1964},
  doi = {10.3133/pp313c},
  url = {https://pubs.usgs.gov/publication/pp313C},
  note = {Source identifier: pp313C}
}