Al-Hawasy, Jamil, Haider H. Diwan, and Waffa F. Keidan. “Constraints Optimal Control Problem For Quaternary Nonlinear Elliptic System”. Academic Science Journal 2, no. 3 (July 1, 2024): 1–15. Accessed September 29, 2025. http://acadscij.uodiyala.edu.iq/index.php/Home/article/view/81.