Interpreting Interactions and Interaction Hierarchies in Generalized Linear Models: Issues and Applications

http://www.artsci.wustl.edu/~jgill/papers/interactions3.pdf

R Functions Things Your Mother (Probably) Didn’t Tell You About

http://www.stat.auckland.ac.nz/~ihaka/downloads/Waikato-WRUG.pdf

Gráficos avanzados con R

http://processtrends.com/Learn_R_Toolkit.htm, http://www2.warwick.ac.uk/fac/sci/moac/people/students/peter_cock/r

Histograma Polar

Histograma Polar, Bonito y útil.