@misc{indiciae3a9032fc63e5,
  title = {Maps showing distribution, composition, and age of early and middle Cenozoic volcanic centers in Idaho, Montana, west-central South Dakota, and Wyoming},
  author = {R. G. Luedke},
  year = {1994},
  doi = {10.3133/i2291c},
  url = {https://pubs.usgs.gov/publication/i2291C},
  note = {Source identifier: i2291C}
}