WARŻAŁA, R. The Importance of Services in Shaping the Volatility and Synchronization of Regional Business Cycles: a Comparative Analysis of the Polish and Portuguese Economies. Olsztyn Economic Journal, [S. l.], v. 21, n. 1, p. 5–26, 2026. DOI: 10.31648/oej.12313. Disponível em: https://czasopisma.uwm.edu.pl/index.php/oej/article/view/12313. Acesso em: 13 mar. 2026.