To cite ptm in publications use:

Aledo J (2021). “ptm: an R package for the study of methionine sulfoxidation and other posttranslational modifications.” Bioinformatics, 37, 3979-3980. doi:10.1093/bioinformatics/btab348.

Corresponding BibTeX entry:

  @Article{,
    title = {{ptm}: an {R} package for the study of methionine
      sulfoxidation and other posttranslational modifications},
    author = {Juan Carlos Aledo},
    journal = {Bioinformatics},
    year = {2021},
    volume = {37},
    pages = {3979-3980},
    doi = {10.1093/bioinformatics/btab348},
  }