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Ahmed, M. “Existence and Uniqueness of the Approximation Solutions To the Boundary Value Problem for Fractional Sturm-Liouville Differential Equations With the Caputo Derivative”. Journal of Humanitarian and Applied Sciences, vol. 8, no. 15, June 2023, pp. 320-7, https://khsj.elmergib.edu.ly/index.php/jhas/article/view/164.