To cite qcc in publications use:

Scrucca, L. (2004). qcc: an R package for quality control charting and statistical process control. R News 4/1, 11-17.

Corresponding BibTeX entry:

  @Article{,
    title = {qcc: an R package for quality control charting and
      statistical process control},
    author = {Luca Scrucca},
    journal = {R News},
    year = {2004},
    pages = {11--17},
    volume = {4/1},
    url = {http://CRAN.R-project.org/doc/Rnews/},
  }