@misc{indiciae6f399df9ac34,
  title = {Fifty-sixth annual report of the Director of the Geological Survey},
  author = {Walter Curran Mendenhall},
  year = {1935},
  doi = {10.3133/ar56},
  url = {https://pubs.usgs.gov/publication/ar56},
  note = {Source identifier: ar56}
}