@misc{indiciae71f33161ed06,
  title = {Geologic mapping in the United States},
  author = {Leona Boardman},
  year = {1949},
  doi = {10.1130/0016-7606(1949)60[1125:gmitus]2.0.co;2},
  url = {https://pubs.usgs.gov/publication/70215519},
  note = {Source identifier: 70215519}
}