@misc{indiciaedc2833ee64d6,
  title = {Estimates of tracer-based piston-flow ages of groundwater from selected sites: National Water-Quality Assessment Program, 1992–2005},
  author = {Stephen R. Hinkle and Stephanie D. Shapiro and Niel Plummer and Eurybiades Busenberg and Peggy K. Widman and Gerolamo C. Casile and Julian E. Wayland},
  year = {2011},
  doi = {10.3133/sir20105229},
  url = {https://pubs.usgs.gov/publication/sir20105229},
  note = {Source identifier: sir20105229}
}