@misc{indiciaefb7949bd7145,
  title = {Aeromagnetic map of Montana},
  author = {Isidore Zietz and Francis P. Gilbert and Stephen L. Snyder},
  year = {1980},
  doi = {10.3133/gp935},
  url = {https://pubs.usgs.gov/publication/gp935},
  note = {Source identifier: gp935}
}