Oczki, Jarosław, i Ewa Wędrowska. 2014. „THE International Competitiveness of European Union COUNTRIES and Strategies FOR ITS EnhancEMENT: A Taxonomic Analysis”. Metody Ilościowe W Badaniach Ekonomicznych 15 (2):167-76. https://qme.sggw.edu.pl/article/view/3680.