@misc{indiciae5450df3ef75b,
  title = {Aeromagnetic map of Montana: In color},
  author = {Isidore Zietz and F. P. Gilbert and S. L. Snyder},
  year = {1980},
  doi = {10.3133/gp934},
  url = {https://pubs.usgs.gov/publication/gp934},
  note = {Source identifier: gp934}
}