Al-hawasy, J. A., & Al-Qaisi, S. J. M. (2019). The Continuous Classical Boundary Optimal Control of a Couple Nonlinear Elliptic Partial Differential Equations with State Constraints. Al-Mustansiriyah Journal of Science, 30(1), 143–151. https://doi.org/10.23851/mjs.v30i1.464