@misc{indiciae667345192b82,
  title = {Herbicides and nitrate in near-surface aquifers in the midcontinental United States, 1991},
  author = {Dana W. Kolpin and Michael R. Burkart and E. Michael Thurman},
  year = {1994},
  doi = {10.3133/wsp2413},
  url = {https://pubs.usgs.gov/publication/wsp2413},
  note = {Source identifier: wsp2413}
}