To cite package ‘ppmSDR’ in publications use:

  Shin J, Shin SJ (2026). _ppmSDR: Penalized Principal Machine for
  Sufficient Dimension Reduction_. R package version 2.0.0,
  <https://github.com/c16267/ppmsdr>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {ppmSDR: Penalized Principal Machine for Sufficient Dimension Reduction},
    author = {Jungmin Shin and Seung Jun Shin},
    year = {2026},
    note = {R package version 2.0.0},
    url = {https://github.com/c16267/ppmsdr},
  }