@book{119766,
	author = {De Jasay, Anthony,},
	title = {Social contract, free ride :},
	publisher = {Oxford University Press,},
	year = {1989.},
	address = {Oxford },
	note = {Includes index.},
	url = {http://www.loc.gov/catdir/enhancements/fy0640/88007647-d.html}
}