@misc{indiciae55d1a7fde188,
  title = {Pre-Pennsylvanian rocks along the Front Range of Colorado},
  author = {John Charles Maher},
  year = {1950},
  doi = {10.3133/oc39},
  url = {https://pubs.usgs.gov/publication/oc39},
  note = {Source identifier: oc39}
}