@book{10306,
	author = {Colman, David. and Young, Trevor.},
	title = {Principles of agricultural economics :},
	publisher = {Cambridge University Press,},
	year = {1989.},
	address = {Cambridge ;},
	note = {Includes index.},
	url = {http://www.loc.gov/catdir/samples/cam031/88010297.html}
}