Hameed, Firas N., and Karim S. Kalaf. “On NM-Hollow Modules”. Journal of Al-Qadisiyah for Computer Science and Mathematics 13, no. 1 (March 4, 2021): Math Page 168– 172. Accessed November 14, 2024. https://jqcsm.qu.edu.iq/index.php/journalcm/article/view/765.