HALIM, HARLIANA, KAMARUZAMAN YUSOFF, SHAKILA AHMAD, MOHD FAIZAL ABDUL KHIR, ABDUL HAFIZ ABDULLAH, AMINUDDIN BASIR, and SYARIFAH KHADIJAH SYED ABU BAKAR. 2018. “SUMBER-SUMBER KAJIAN TERHADAP KEWUJUDAN NEGARA ISLAM VOLGA BULGARIA 922 MASEHI”. Human Sustainability Procedia, May. https://publisher.uthm.edu.my/periodicals/index.php/hsp/article/view/1186.