Litovchenko, V. A. “On the Correct Solvability of One Cauchy Problem”. Ukrains’kyi Matematychnyi Zhurnal 54, no. 8 (August 25, 2002): 1067-1076. Accessed May 9, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4147.