The Problem of the Optimal Control with a Lower Coefficient for Weakly Nonlinear Wave Equation in the Mixed Problem. Eur. J. Pure Appl. Math. [Internet]. 2020 Apr. 29 [cited 2024 Dec. 22];13(2):314-22. Available from: https://www.ejpam.com/index.php/ejpam/article/view/3650