@misc{indiciae751442699ba1,
  title = {Preliminary geologic map of the Gray Head quadrangle, San Miguel County, Colorado},
  author = {A.L. Bush and C. S. Bromfield and O.T. Marsh and R.B. Taylor},
  year = {1961},
  doi = {10.3133/mf176},
  url = {https://pubs.usgs.gov/publication/mf176},
  note = {Source identifier: mf176}
}