@misc{indiciae7fdfa9b8f78e,
  title = {Estimates of tracer-based piston-flow ages of groundwater from selected sites: National Water-Quality Assessment Program, 2006-2010},
  author = {Stephanie D. Shapiro and Niel Plummer and Eurybiades Busenberg and Peggy K. Widman and Gerolamo C. Casile and Julian E. Wayland and Donna L. Runkle},
  year = {2012},
  doi = {10.3133/sir20125141},
  url = {https://pubs.usgs.gov/publication/sir20125141},
  note = {Source identifier: sir20125141}
}