@misc{indiciae4db379d2aa16,
  title = {Map showing outstanding natural and historic landmarks in the Boulder-Fort Collins-Greeley area, Front Range Urban Corridor, Colorado},
  author = {B. N. Petrie},
  year = {1975},
  doi = {10.3133/i855f},
  url = {https://pubs.usgs.gov/publication/i855F},
  note = {Source identifier: i855F}
}