@misc{indiciae6dcb1cedffc5,
  title = {The Carboniferous formations and faunas of Colorado},
  author = {G.H. Girty},
  year = {1903},
  doi = {10.3133/pp16},
  url = {https://pubs.usgs.gov/publication/pp16},
  note = {Source identifier: pp16}
}