@misc{indiciaecb0688bc37aa,
  title = {Plotting and regression programs for isotope geochemists, for use with HP-86/87 microcomputers},
  author = {K.R. Ludwig},
  year = {1983},
  doi = {10.3133/ofr83849},
  url = {https://pubs.usgs.gov/publication/ofr83849},
  note = {Source identifier: ofr83849}
}