@misc{indiciaef79be938a83a,
  title = {Preliminary geologic map and coal sections of the Twin Buttes Quadrangle, Prairie and Custer counties, Montana},
  author = {E. J. McKay and F.W. Mason},
  year = {1975},
  doi = {10.3133/mf725},
  url = {https://pubs.usgs.gov/publication/mf725},
  note = {Source identifier: mf725}
}