Nomirovs’kii, D. A. “Solvability and Trajectory-Final Controllability of Pseudohyperbolic Systems”. Ukrains’kyi Matematychnyi Zhurnal 57, no. 3 (March 25, 2005): 366–376. Accessed May 25, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3604.