@book{2550,
	author = {Samuelson, P.A. & W. D. Nordhaus and P.A. Samuelson & W. D. Nordhaus},
	title = {Economics},
	publisher = {Mc Grow Hill},
	year = {2005},
	address = {New York},
	edition = {18 th},
	note = {Includes Index}
}