R http://ww2.coastal.edu/kingw/statistics/R-tutorials/preliminaries.html

http://ww2.coastal.edu/kingw/statistics/R-tutorials/preliminaries.html

http://wiener.math.csi.cuny.edu/Statistics/R/simpleR/stat016.html

http://wiener.math.csi.cuny.edu/Statistics/R/simpleR/stat016.html