Now that we have covered everything, let's take a look at some external references for further reading:
Bivand, R. S., Pebesma, E. J., and Gómez-Rubio, V. Applied Spatial Data Analysis with R Second Edition. Springer. 2013.
Chang, W. R Graphics Cookbook. O'Reilly Media. 2012.
Cowpertwait, P. S. P. and Metcalfe, A. V. Introductory Time Series with R. Springer. 2009.
Diggle, P. and Ribeiro, P. J. Model-based Geostatistics. Springer. 2007.
Grolemund, G. and Wickham, H. "Dates and Times Made Easy with lubridate". Journal of Statistical Software. 2011. http://www.jstatsoft.org/v40/i03/paper.
Hengl, T. "A practical guide to geostatistical mapping of environmental variables". JRC Scientific and Technical Reports. 2007. http://spatial-analyst.net/book/.