@misc{indiciaea8835012980a,
  title = {Geologic map of Colorado},
  author = {W. S. Burbank and T. S. Lovering and E. N. Goddard and E.B. Eckel},
  year = {1935},
  doi = {10.3133/70210880},
  url = {https://pubs.usgs.gov/publication/70210880},
  note = {Source identifier: 70210880}
}