@book{24891,
	author = {Varian, Hal R. and Farrell, Joseph},
	title = {The economics of information technology :},
	publisher = {Cambridge University Press,},
	year = {2004.},
	series = {The Raffaele Mattioli lecture series},
	address = {Cambridge ;},
	url = {http://www.loc.gov/catdir/enhancements/fy0632/2005279623-d.html}
}