@misc{indiciae2ad11a17f7d9,
  title = {The Pierre Shale near Kremmling, Colorado, and its correlation to the east and the west},
  author = {G. A. Izett and W. A. Cobban and J. R. Gill},
  year = {1971},
  doi = {10.3133/pp684a},
  url = {https://pubs.usgs.gov/publication/pp684A},
  note = {Source identifier: pp684A}
}