http://pubdocs.worldbank.org/en/244481520499464074/Growing-United-v03-online-18-03-08.pdf
https://blogs.lse.ac.uk/europpblog/2023/04/13/ever-closer-union-and-the-philosophical-history-of-europe/
https://ec.europa.eu/commission/sites/beta-political/files/communication-credible-enlargement-perspective-western-balkans_en.pdf