Tepoyan, L.P., and H.S. Grigoryan. 2012. “ON DEGENERATE NONSELF-ADJOINT DIFFERENTIAL EQUATIONS OF FOURTH ORDER”. Proceedings of the YSU A: Physical and Mathematical Sciences 46 (3 (229). Yerevan, Armenia:29-33. https://doi.org/10.46991/PYSU:A/2012.46.3.029.