FOLFAS, Paweł. Regions in the United States and the European Union - GDP per Capita, Convergence Processes and Spatial Dependencies. DEMO, Poland, v. 5, n. 1, p. 75–85, 2017. DOI: 10.18559/SOEP.2017.1.5. Disponível em: https://ojs34.fimagis.pl/index.php/demo/article/view/962. Acesso em: 14 may. 2026.