Abdelkader, Salim Bourchid, Hamidouche M’hamed, and Abderrazak Ahmed Zian. “Concentration and Specialization of Economic Activities in the Kingdom of Saudi Arabia”. Shirkah: Journal of Economics and Business 5, no. 3 (December 28, 2020): 362–385. Accessed February 24, 2025. https://shirkah.or.id/new-ojs/index.php/home/article/view/348.