Khneab , A. S. .; Al-hawasy, J. A.; Chryssoverghi , I. Quaternary Boundary Optimal Control Problem for Quaternary Nonlinear Elliptic System With Constraints. Al-Mustansiriyah J. Sci. 2024, 35 (4), 31-41. https://doi.org/10.23851/mjs.v35i4.1546.