To cite package ‘ssrn’ in publications use:

  Uryu S, Tanoue Y, Yoneoka D (2020). _ssrn: Scan Statistics for
  Railway Network_. R package version 0.1.0,
  <https://github.com/uribo/ssrn>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {ssrn: Scan Statistics for Railway Network},
    author = {Shinya Uryu and Yuta Tanoue and Daisuke Yoneoka},
    year = {2020},
    note = {R package version 0.1.0},
    url = {https://github.com/uribo/ssrn},
  }