Aziz Hussan Al – Abdulla, Raad, and Karim Fadhil Al – Omri. “On Β*c– Open Set and Its Properties”. Journal of Al-Qadisiyah for Computer Science and Mathematics 11, no. 1 (October 21, 2018): Math Page 27 – 35. Accessed November 15, 2024. https://jqcsm.qu.edu.iq/index.php/journalcm/article/view/447.