Economic growth / Robert J. Barro, Xavier Sala-i-Martin. Barro, Robert J. Sala-i-Martin, Xavier. Economic development Mathematical models. HD75.5 .B37 2004 338.9 22 BAE Includes bibliographical references p. 627-640 and index. Cambridge, Mass. : MIT, c2004. c2004. 2004 Text xvi, 654 p. : eng