@misc{indiciae2e187db9bb4b,
  title = {Forty-first annual report of the Director of the United States Geological Survey},
  author = {George Otis Smith},
  year = {1920},
  doi = {10.3133/ar41},
  url = {https://pubs.usgs.gov/publication/ar41},
  note = {Source identifier: ar41}
}