Kovalev, A. M., and V. F. Shcherbak. “Conditions of Unique Solvability for the Inverse Problems in Controlled Dynamical Systems”. Ukrains’kyi Matematychnyi Zhurnal 44, no. 10 (October 1, 1992): 1359–1366. Accessed April 14, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/8232.