@misc{indiciaea3f1cb3baf0b,
  title = {Coal resources of Montana},
  author = {John Xavier Combo and D.M. Brown and H.F. Pulver and D.A. Taylor},
  year = {1949},
  doi = {10.3133/cir53},
  url = {https://pubs.usgs.gov/publication/cir53},
  note = {Source identifier: cir53}
}