Nitrates webpage Minnesota Department of Health
https://www.health.state.mn.us/communities/environment/water/contaminants/nitrate.html
Document Tag: Nitrates
Nitrates webpage Centers for Disease Control and Prevention
https://www.cdc.gov/healthywater/drinking/private/wells/disease/nitrate.html
Nitrates webpage Penn State University Extension
https://extension.psu.edu/nitrates-in-drinking-water
Nitrates factsheet Cornell Cooperative Extension
http://psep.cce.cornell.edu/facts-slides-self/facts/nit-heef-grw85.aspx