Khajiev I.O, Mamatqulova M.Sh, and Komiljonova G.A. “Conditional Correctness of the Initial-Boundary Value Problem for The System of Second Order Mixed Type Equations”. Eurasian Journal of Physics,Chemistry and Mathematics, vol. 17, Apr. 2023, pp. 47-57, https://geniusjournals.org/index.php/ejpcm/article/view/3984.