Derev’yanko, N. V., and V. M. Kirilich. “Problem of Optimal Control for a Semilinear Hyperbolic System of Equations of the First Order With Infinite Horizon Planning”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 67, no. 2, Feb. 2015, pp. 185–201, https://umj.imath.kiev.ua/index.php/umj/article/view/1973.