@misc{indiciae1ec78bb1e7d5,
  title = {Structure contour map of the Powder River Basin, Wyoming and Montana},
  author = {William Gamewell Pierce and Roselle M. Girard and Alfred Dexter Revised by Zapp},
  year = {1945},
  doi = {10.3133/om133},
  url = {https://pubs.usgs.gov/publication/om133},
  note = {Source identifier: om133}
}