@misc{indiciae48b2395e807f,
  title = {Geologic map of the Boulder quadrangle, Boulder County, Colorado},
  author = {Chester T. Wrucke and Richard F. Wilson},
  year = {1967},
  doi = {10.3133/ofr67281},
  url = {https://pubs.usgs.gov/publication/ofr67281},
  note = {Source identifier: ofr67281}
}