@misc{indiciaeb12c7f60baeb,
  title = {Geology of the Navajo country: A reconnaissance of parts of Arizona, New Mexico, and Utah},
  author = {H. E. Gregory},
  year = {1917},
  doi = {10.3133/pp93},
  url = {https://pubs.usgs.gov/publication/pp93},
  note = {Source identifier: pp93}
}