@misc{indiciae31495c8ba26c,
  title = {Geology and ore deposits of the La Plata district, Colorado},
  author = {E.B. Eckel},
  year = {1949},
  doi = {10.3133/pp219},
  url = {https://pubs.usgs.gov/publication/pp219},
  note = {Source identifier: pp219}
}