@misc{indiciaea0b641766e91,
  title = {Concentrations and possible sources of nitrate in water from the Silurian-Devonian aquifer, Cedar Falls, Iowa},
  author = {Bryan D. Schaap},
  year = {1999},
  doi = {10.3133/wri994106},
  url = {https://pubs.usgs.gov/publication/wri994106},
  note = {Source identifier: wri994106}
}