@misc{indiciaef40a7767884e,
  title = {Geology of the igneous rocks of the Spanish Peaks region, Colorado},
  author = {R. B. Johnson},
  year = {1968},
  doi = {10.3133/pp594g},
  url = {https://pubs.usgs.gov/publication/pp594G},
  note = {Source identifier: pp594G}
}