El-Zahaby, S.A., and Ibtissam El-Zoulati. “Optimal Control Problem Governed By Elliptic Variational Inequalities For Infinite Order”. Journal of Progressive Research in Mathematics 6, no. 4 (February 26, 2016): 842-848. Accessed March 14, 2025. http://scitecresearch.com/journals/index.php/jprm/article/view/605.