@misc{indiciaeca9093eda863,
  title = {Thirty-third annual report of the Director of the United States Geological Survey},
  author = {George Otis Smith},
  year = {1912},
  doi = {10.3133/ar33},
  url = {https://pubs.usgs.gov/publication/ar33},
  note = {Source identifier: ar33}
}