To cite package ‘qrencoder’ in publications use:

Rudis B (2018). qrencoder: Quick Response Code (QR Code) / Matrix Barcode Creator. R package version 0.2.1, https://github.com/hrbrmstr/qrencoder.

Corresponding BibTeX entry:

  @Manual{,
    title = {qrencoder: Quick Response Code (QR Code) / Matrix Barcode
      Creator},
    author = {Bob Rudis},
    year = {2018},
    note = {R package version 0.2.1},
    url = {https://github.com/hrbrmstr/qrencoder},
  }