@misc{indiciaeb5555f7ff109,
  title = {County-level estimates of nitrogen and phosphorus fertilizer use in the United States, 1945 to 1985},
  author = {Richard B. Alexander and Richard A. Smith},
  year = {1990},
  doi = {10.3133/ofr90130},
  url = {https://pubs.usgs.gov/publication/ofr90130},
  note = {Source identifier: ofr90130}
}