kadham Al-talkany, Yiezi, Ameer A.J. AL-Swidi, and Ali Younis Shaker. 2017. “Topological Study via σ-Algebra”. Journal of Al-Qadisiyah for Computer Science and Mathematics 8 (1):78-82. https://jqcsm.qu.edu.iq/index.php/journalcm/article/view/46.