@misc{indiciaed7c504349fd8,
  title = {Nitrate in the Mississippi River and its tributaries, 1980-2010: an update},
  author = {Jennifer C. Murphy and Robert M. Hirsch and Lori A. Sprague},
  year = {2013},
  doi = {10.3133/sir20135169},
  url = {https://pubs.usgs.gov/publication/sir20135169},
  note = {Source identifier: sir20135169}
}