To cite package 'nppbib' in publications use:

Allingham D, Best D (2020). nppbib: Nonparametric Analysis of Partially-Balanced Incomplete Block Designs. R package version 1.2-0.

Corresponding BibTeX entry:

  @Manual{,
    title = {nppbib: Nonparametric Analysis of Partially-Balanced
      Incomplete Block Designs},
    author = {David Allingham and D.J. Best},
    year = {2020},
    note = {R package version 1.2-0},
  }