To cite package ‘duckduckr’ in publications use:

Schumacher D (2017). duckduckr: Simple Client for the DuckDuckGo Instant Answer API. R package version 1.0.0.9000, https://github.com/dirkschumacher/duckduckr.

Corresponding BibTeX entry:

  @Manual{,
    title = {duckduckr: Simple Client for the DuckDuckGo Instant Answer
      API},
    author = {Dirk Schumacher},
    year = {2017},
    note = {R package version 1.0.0.9000},
    url = {https://github.com/dirkschumacher/duckduckr},
  }