@misc{indiciaef5a683b10e6c,
  title = {Gravel resources, urbanization, and future land use, Front Range Urban Corridor, Colorado},
  author = {James M. Soule and Harold R. Fitch},
  year = {1974},
  doi = {10.3133/ofr74178},
  url = {https://pubs.usgs.gov/publication/ofr74178},
  note = {Source identifier: ofr74178}
}