@book{15224,
	author = {George, Darren ; Mallery, Paul},
	title = {SPSS for Windows Step by Step: a simple guide and reference 17.0 update},
	publisher = {Pearson Education Inc},
	year = {,2011.},
	address = {Uttar Pradesh:},
	edition = {10th},
	note = {Includes Index}
}