Abbass, Husein Hadi, Shatha Abdul-Hussein Kadhim, and Ali Hussein Battor. “On Normal Subgroups Lattice of Dihedral Group”. Journal of Al-Qadisiyah for Computer Science and Mathematics 12, no. 1 (March 11, 2020): Math Page 83– 95. Accessed November 13, 2024. https://jqcsm.qu.edu.iq/index.php/journalcm/article/view/675.