@misc{indiciae88a59334a148,
  title = {Geologic and structure map, with contours on top of the Pierre Shale, for the north half of the Powder River basin, southeastern Montana and northeastern Wyoming},
  author = {N.M. Denson and M.L. Gibson and G.L. Sims},
  year = {1993},
  doi = {10.3133/i2343a},
  url = {https://pubs.usgs.gov/publication/i2343A},
  note = {Source identifier: i2343A}
}