@book{51715,
	author = {Baumol, William J. and ebrary, Inc.},
	title = {Convergence of productivity},
	publisher = {Oxford Unviersity Press,},
	year = {c1994.},
	address = {New York :},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=10087211}
}