@misc{indiciaefcdaa5a396c2,
  title = {Structure contour map of the Powder River Basin, Wyoming and Montana},
  author = {William Gamewell Pierce and Roselle M. Girard},
  year = {1945},
  doi = {10.3133/om33},
  url = {https://pubs.usgs.gov/publication/om33},
  note = {Source identifier: om33}
}