@misc{indiciae689f68a82dbc,
  title = {Geologic map of the Black Rock Wilderness Study Area, Graham County, Arizona},
  author = {F. S. Simons},
  year = {1987},
  doi = {10.3133/mf1918},
  url = {https://pubs.usgs.gov/publication/mf1918},
  note = {Source identifier: mf1918}
}