To cite package ‘zlib’ in publications use:

  Geist S (2023). _zlib: Compression and Decompression_. R package
  version 1.0.3, <https://CRAN.R-project.org/package=zlib>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {zlib: Compression and Decompression},
    author = {Semjon Geist},
    year = {2023},
    note = {R package version 1.0.3},
    url = {https://CRAN.R-project.org/package=zlib},
  }