@misc{indiciae5215645ba34c,
  title = {Geology of the Mount Aetna volcanic center, Chaffee and Gunnison Counties, Colorado},
  author = {Priestley Toulmin and Jane Marie Hammarstrom},
  year = {1990},
  doi = {10.3133/b1864},
  url = {https://pubs.usgs.gov/publication/b1864},
  note = {Source identifier: b1864}
}