H. Bulut, Y. Öner, and Çağlar Sözen, “Clustering of Member and Candidate Countries of the European Union”, IJSBAR, vol. 36, no. 7, pp. 18–25, Dec. 2017, Accessed: Jan. 14, 2026. [Online]. Available: https://www.gssrr.org/JournalOfBasicAndApplied/article/view/8274