p. 580, in George Reisman, Capitalism:A Treatise on Economics, 1990, Jameson Books, Ottawa, Illinois. ISBN 0-915463-73-3; Versio pdf gratis praebita hic:http://www.capitalism.net/
Raymond Torres, OECD head of Employment Analysis, Le Monde, 30 mai 2007: unemployment measure is less and less meaningful to measure labour market efficiency.