Progress in nominal and real convergence will imply an orderly closing of the gap between the accession countries and the euro area economy, both in terms of per capita income and price levels. In order to reinforce each other, nominal and real convergence paths must be properly sequenced and mutually balanced.
There are also  5  Diebold, F. X., G. Rudebusch and S. B. Arouba, (2006), “The macroeconomy and the yield curve: a dynamic latent factor approach”, Journal of Econometrics, 131, 309–338. 6  Rudebusch, G. and T. Wu (2007) “Accounting for a shift in term structure behaviour with no-arbitrage and macro-finance models”, Journal of Money, Credit and Banking, 39, 395–422.