@misc{indiciaeb92aed5f8a8a,
  title = {Map showing contours on the top of the Pennsylvanian and Permian Minnelusa Formation and equivalents, Powder River basin, Wyoming and Montana},
  author = {B.L. Crysdale},
  year = {1990},
  doi = {10.3133/mf2140b},
  url = {https://pubs.usgs.gov/publication/mf2140B},
  note = {Source identifier: mf2140B}
}