А.Sh. Shaldanbayev, A.B. Imanbayeva, A.Zh. Beisebayeva, & А.А. Shaldanbayeva. (2019). ON THE SQUARE ROOT OF THE OPERATOR OF STURM-LIOUVILLE FOURTH-ORDER. Известия НАН РК. Серия физико-математическая, (3), 85–96. извлечено от http://89.250.84.46/physics-mathematics/article/view/1637