“Fractional Helmholtz and Fractional Wave Equations With Riesz-Feller and Generalized Riemann-Liouville Fractional Derivatives”. European Journal of Pure and Applied Mathematics 7, no. 3 (August 1, 2014): 312–334. Accessed April 30, 2024. https://www.ejpam.com/index.php/ejpam/article/view/2176.