To cite ggplot2 in publications, please use:

H. Wickham. ggplot2: elegant graphics for data analysis. Springer New York, 2009.

Corresponding BibTeX entry:

  @Book{,
    author = {Hadley Wickham},
    title = {ggplot2: elegant graphics for data analysis},
    publisher = {Springer New York},
    year = {2009},
    isbn = {978-0-387-98140-6},
    url = {http://had.co.nz/ggplot2/book},
  }