@misc{indiciae21c75175a8b7,
  title = {Maps showing distribution, composition, and age of early and middle Cenozoic volcanic centers in Oregon and Washington},
  author = {R. G. Luedke},
  year = {1998},
  doi = {10.3133/i2291d},
  url = {https://pubs.usgs.gov/publication/i2291D},
  note = {Source identifier: i2291D}
}