T. Luma, N., and I. G. Iman. “Explicit Difference Method for Solving the Two-Dimensional Two-Sided Fractional Diffusion Equation in the Shifted Grunwald Estimate Form”. Scientific Journal of Pure and Applied Sciences, vol. 2, no. 9, Sept. 2013, pp. 314-22, http://sjournals.com/index.php/sjpas/article/view/965.