To cite package ‘currencyapi’ in publications use:

Kukacka D (2023). currencyapi: Client for the 'currencyapi.com' Currency Conversion API. R package version 0.1.0, https://CRAN.R-project.org/package=currencyapi.

Corresponding BibTeX entry:

  @Manual{,
    title = {currencyapi: Client for the 'currencyapi.com' Currency
      Conversion API},
    author = {Dominik Kukacka},
    year = {2023},
    note = {R package version 0.1.0},
    url = {https://CRAN.R-project.org/package=currencyapi},
  }