To cite package ‘gtheory’ in publications use:

  Moore CT (2016). _gtheory: Apply Generalizability Theory with R_. R
  package version 0.1.2,
  <https://github.com/cranhaven/cranhaven.r-universe.dev>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {gtheory: Apply Generalizability Theory with R},
    author = {Christopher T. Moore},
    year = {2016},
    note = {R package version 0.1.2},
    url = {https://github.com/cranhaven/cranhaven.r-universe.dev},
  }