Baskakov, Anatoly, Ilya Krishtal, and Natalya Borisovna Uskova. “On the Spectral Analysis of a Differential Operator With an Involution and General Boundary Conditions”. Eurasian Mathematical Journal 11, no. 2 (June 30, 2020): 30–39. Accessed September 30, 2026. https://emj.enu.kz/index.php/main/article/view/176.