@misc{indiciae17b7812422bd,
  title = {Instructions for US P-61-A1 suspended-sediment sampler},
  author = {V.C. Colby and F.W. Witzgman},
  year = {1962},
  url = {https://pubs.usgs.gov/publication/70170554},
  note = {Source identifier: 70170554}
}