30 Robert J. Barro et Xavier Sala i Martin &quot; Convergence accross States and regions &quot; , Brookings Papers on Economic Activity (1), 1991; &quot; Convergence &quot; , Journal of Political Economy (avril 1992); et Steve Dowrick et Duc-Tho Nguyen, &quot; OECD comparative economic growth 1950-85: catch-up and convergence &quot; , American Economic Review (décembre 1989).
30/ Robert J. Barro and Xavier Sala i Martin, &quot; Convergence across States and regions &quot; , Brookings Papers on Economic Activity (1), 1991; &quot; Convergence &quot; , Journal of Political Economy (April 1992); и Steve Dowrick and Duc-Tho Nguyen, &quot; OECD comparative economic growth 1950-85: catch-up and convergence &quot; , American Economic Review (December 1989).