To cite package ‘ggkegg’ in publications use:

  Sato N, Uematsu M, Fujimoto K, Uematsu S, Imoto S. ggkegg: analysis
  and visualization of KEGG data utilizing the grammar of graphics.
  Bioinformatics. 2023 Oct 3;39(10):btad622.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {ggkegg: analysis and visualization of KEGG data utilizing the grammar of graphics},
    author = {Noriaki Sato and Miho Uematsu and Kosuke Fujimoto and Satoshi Uematsu and Seiya Imoto},
    journal = {Bioinformatics},
    year = {2023},
    volume = {39},
    number = {10},
    pages = {btad622},
    pmid = {37846038},
    doi = {10.1093/bioinformatics/btad622},
  }