@misc{indiciaef0e11634fcd4,
  title = {Preliminary structure contour map of Blaine, northern Choteau, and Hill Counties and adjoining areas in Montana},
  author = {C.E. Erdman and V.E. Koskinen},
  year = {1953},
  doi = {10.3133/ofr5361},
  url = {https://pubs.usgs.gov/publication/ofr5361},
  note = {Source identifier: ofr5361}
}