@misc{indiciae96ed1112b675,
  title = {County-level estimates of nitrogen and phosphorus from commercial fertilizer for the Conterminous United States, 1987-2006},
  author = {Jo Ann M. Gronberg and Norman E. Spahr},
  year = {2012},
  doi = {10.3133/sir20125207},
  url = {https://pubs.usgs.gov/publication/sir20125207},
  note = {Source identifier: sir20125207}
}