@misc{indiciae9ebbe450dc9c,
  title = {Subsurface stratigraphy of Paleozoic rocks in southeastern Montana and adjacent parts of Wyoming and South Dakota},
  author = {Constance Leatherock},
  year = {1950},
  doi = {10.3133/oc40},
  url = {https://pubs.usgs.gov/publication/oc40},
  note = {Source identifier: oc40}
}