@misc{indiciae8618d99d21c0,
  title = {Calderas of the San Juan volcanic field, southwestern Colorado},
  author = {Thomas August Steven and Peter W. Lipman},
  year = {1975},
  doi = {10.3133/pp958},
  url = {https://pubs.usgs.gov/publication/pp958},
  note = {Source identifier: pp958}
}