@misc{indiciae4ecb22121cab,
  title = {Estimating background and threshold nitrate concentrations using probability graphs},
  author = {S.V. Panno and W.R. Kelly and A.T. Martinsek and Keith C. Hackley},
  year = {2006},
  doi = {10.1111/j.1745-6584.2006.00240.x},
  url = {https://pubs.usgs.gov/publication/70028392},
  note = {Source identifier: 70028392}
}