@misc{indiciaec90194aa3656,
  title = {Detailed sections of pre-Pennsylvanian rocks along the Front Range of Colorado},
  author = {John Charles Maher},
  year = {1950},
  doi = {10.3133/cir68},
  url = {https://pubs.usgs.gov/publication/cir68},
  note = {Source identifier: cir68}
}