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, vol. 9, no. 3, Aug. 2023, pp. 790-01, doi:10.35326/pencerah.v9i3.2922.