@misc{indiciaec589f9a7ff20,
  title = {Geology and petrology of the San Juan region, southwestern Colorado},
  author = {E. S. Larsen and Whitman Cross},
  year = {1956},
  doi = {10.3133/pp258},
  url = {https://pubs.usgs.gov/publication/pp258},
  note = {Source identifier: pp258}
}