@misc{indiciaefdc9109ce452,
  title = {Glacial map of Montana east of the Rocky Mountains},
  author = {R. B. Colton and R. W. Lemke and R. M. Lindvall},
  year = {1961},
  doi = {10.3133/i327},
  url = {https://pubs.usgs.gov/publication/i327},
  note = {Source identifier: i327}
}