@misc{indiciae9efc9827e3cc,
  title = {Map showing outstanding natural and historic landmarks in the greater Denver area, Front Range Urban Corridor, Colorado},
  author = {B. N. Petrie},
  year = {1976},
  doi = {10.3133/i856f},
  url = {https://pubs.usgs.gov/publication/i856F},
  note = {Source identifier: i856F}
}