HALIM, H.; YUSOFF, K.; AHMAD, S.; ABDUL KHIR, M. F.; ABDULLAH, A. H.; BASIR, A.; SYED ABU BAKAR, S. K. SUMBER-SUMBER KAJIAN TERHADAP KEWUJUDAN NEGARA ISLAM VOLGA BULGARIA 922 MASEHI. Human Sustainability Procedia, [S. l.], 2018. Disponível em: https://publisher.uthm.edu.my/periodicals/index.php/hsp/article/view/1186. Acesso em: 1 jul. 2022.