@book{20,
	author = {Bryman, Alan. and Cramer, Duncan,},
	title = {Quantitative data analysis with SPSS 12 and 13 :},
	publisher = {Routledge,},
	year = {2005.},
	address = {London ;},
	url = {http://www.loc.gov/catdir/enhancements/fy0651/2004011860-d.html}
}