Tepoyan, L.P., and H.S. Grigoryan. “ON DEGENERATE NONSELF-ADJOINT DIFFERENTIAL EQUATIONS OF FOURTH ORDER”. Proceedings of the YSU A: Physical and Mathematical Sciences 46, no. 3 (229) (December 1, 2012): 29–33. Accessed November 22, 2024. https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol46_no3_2012_pp029-033.