To cite package 'aws.polly' in publications use:

Leeper TJ (2020). aws.polly: Client for AWS Polly. R package version 0.1.5.

Corresponding BibTeX entry:

  @Manual{,
    title = {aws.polly: Client for AWS Polly},
    author = {Thomas J. Leeper},
    year = {2020},
    note = {R package version 0.1.5},
  }