To cite package 'meta' in publications use:

Balduzzi S, Rücker G, Schwarzer G (2019). “How to perform a meta-analysis with R: a practical tutorial.” Evidence-Based Mental Health, 153–160.

DOI: 10.1136/ebmental-2019-300117

Corresponding BibTeX entry:

  @Article{,
    title = {How to perform a meta-analysis with {R}: a practical
      tutorial},
    author = {Sara Balduzzi and Gerta Rücker and Guido Schwarzer},
    journal = {Evidence-Based Mental Health},
    year = {2019},
    number = {22},
    pages = {153--160},
  }