To cite package 'metap' in publications use:

Dewey M (2020). metap: meta-analysis of significance values. R package version 1.3.

Corresponding BibTeX entry:

  @Manual{,
    title = {{metap}: meta-analysis of significance values},
    author = {Michael Dewey},
    year = {2020},
    note = {R package version 1.3},
  }