@book{35520,
	author = {Wickham, Hadley. and SpringerLink (Online service)},
	title = {ggplot2},
	publisher = {Springer New York,},
	year = {2009.},
	series = {Use R},
	address = {New York, NY :},
	url = {http://dx.doi.org/10.1007/978-0-387-98141-3}
}