Ibrahim, Sobhy El-Sayed. “On the General Ordinary Quasi-Differential Operators With their\(L_{w}^{2}-\)Solutions and Their Spectra”. Novel Research Aspects in Mathematical and Computer Science Vol. 5 (June 28, 2022): 146–164. Accessed June 4, 2026. https://stm.bookpi.org/NRAMCS-V5/article/view/7489.