Ansari, Hosein. “DEGENERATE DIFFERENTIAL-OPERATOR EQUATIONS ON INFINITE INTERVAL”. Proceedings of the YSU A: Physical and Mathematical Sciences 45, no. 2 (225) (April 28, 2011): 27–32. Accessed July 22, 2024. https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol45_no2_2011_pp027-032.