@misc{indiciae8ee9e0a66d9a,
  title = {Analysis and interpretation of water-quality trends in major U.S. rivers, 1974-81},
  author = {Richard A. Smith and Richard B. Alexander and M. Gordon Wolman},
  year = {1987},
  doi = {10.3133/wsp2307},
  url = {https://pubs.usgs.gov/publication/wsp2307},
  note = {Source identifier: wsp2307}
}