@misc{indiciae93aa69085393,
  title = {Regional patterns in the isotopic composition of natural and anthropogenic nitrate in groundwater, High Plains, U.S.A.},
  author = {P.B. McMahon and J.K. Böhlke},
  year = {2006},
  doi = {10.1021/es052229q},
  url = {https://pubs.usgs.gov/publication/70030472},
  note = {Source identifier: 70030472}
}