@misc{indiciaeaa31b5f7adbe,
  title = {Geologic map of the Grand Valley quadrangle, Garfield County, Colorado},
  author = {John R. Donnell and Warren E. Yeend},
  year = {1968},
  doi = {10.3133/ofr6877},
  url = {https://pubs.usgs.gov/publication/ofr6877},
  note = {Source identifier: ofr6877}
}