@misc{indiciaea9a6192096d2,
  title = {Report of the Geological Exploration of the Fortieth Parallel, Volume VI: Microscopical petrography},
  author = {Ferdinand Zirkel and Clarence King},
  year = {1876},
  doi = {10.3133/70039233},
  url = {https://pubs.usgs.gov/publication/70039233},
  note = {Source identifier: 70039233}
}