@misc{indiciae9dcf9755f90c,
  title = {Automated, colorimetric methods for determination of nitrate plus nitrite, nitrite, ammonium and orthophosphate ions in natural water samples},
  author = {Ronald C. Antweiler and Charles J. Patton and Howard E. Taylor},
  year = {1996},
  doi = {10.3133/ofr93638},
  url = {https://pubs.usgs.gov/publication/ofr93638},
  note = {Source identifier: ofr93638}
}