“DIVERSIFYING THE LEVEL OF SUSTAINABLE DEVELOPMENT IN POLAND AND SELECTED COUNTRIES OF THE EUROPEAN UNION” (2019) Research Bulletins of the Faculty of Economic Sciences, 1(23), pp. 139–158. Available at: https://ezeszyty.wne.tu.koszalin.pl/index.php/zeszyty/article/view/148 (Accessed: 19 July 2025).