To cite zoom in publications use:

Barbu CM (2014). zoom: A spatial data visualization tool. (Version 2.0.6), https://github.com/cbarbu/R-package-zoom.

Corresponding BibTeX entry:

  @Manual{,
    title = {zoom: A spatial data visualization tool},
    author = {Corentin M Barbu},
    year = {2014},
    note = {(Version 2.0.6)},
    url = {https://github.com/cbarbu/R-package-zoom},
  }