Pulungan, Eska Dwipayana. “The Widening of European Union to Post Soviet Countries: Case Study of Bulgaria Acceptance and Ukraine Accession”. Sang Pencerah: Jurnal Ilmiah Universitas Muhammadiyah Buton 9, no. 3 (August 5, 2023): 790–801. Accessed July 23, 2024. https://jurnal-umbuton.ac.id/index.php/Pencerah/article/view/2922.