Sarsenbi A. Unconditional basicity of eigenfunctions’ system of Sturm-Liouville operator with an involutional perturbation. M [Internet]. 2018 Sep. 29 [cited 2025 Sep. 16];91(3):117-2. Available from: https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/306