@misc{indiciaefea01c2aaf79,
  title = {Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003},
  author = {P.B. McMahon and J.K. Böhlke and C. P. Carney},
  year = {2007},
  doi = {10.3133/sir20065294},
  url = {https://pubs.usgs.gov/publication/sir20065294},
  note = {Source identifier: sir20065294}
}