@misc{indiciaeb441b06c65e3,
  title = {Instruction manual for U.S. Geological Survey sediment observers},
  author = {Gary P. Johnson},
  year = {1997},
  doi = {10.3133/ofr96431},
  url = {https://pubs.usgs.gov/publication/ofr96431},
  note = {Source identifier: ofr96431}
}