@misc{indiciae228698670fba,
  title = {Some geologic features of the Pima mining district, Pima County, Arizona},
  author = {John Roberts Cooper},
  year = {1960},
  doi = {10.3133/b1112c},
  url = {https://pubs.usgs.gov/publication/b1112C},
  note = {Source identifier: b1112C}
}