@misc{indiciaef7d9acf47d4f,
  title = {Preliminary unevaluated geologic map of the Ledger-Dunkirk area, Pondera and Toole Counties, Montana},
  author = {K. H. Holmes and T. E. Bretz},
  year = {1978},
  doi = {10.3133/ofr781041},
  url = {https://pubs.usgs.gov/publication/ofr781041},
  note = {Source identifier: ofr781041}
}