To cite package 'muRL' in publications use:

Moore RT, Reeves A (2019). muRL: Mailmerge using R, LateX, and the Web. R package version 0.1-12.

Corresponding BibTeX entry:

  @Manual{,
    title = {muRL: Mailmerge using R, LateX, and the Web},
    author = {Ryan T. Moore and Andrew Reeves},
    year = {2019},
    note = {R package version 0.1-12},
  }