Xuelei Lin, Michael K. Ng and Haiwei Sun. (2018). A Separable Preconditioner for Time-Space Fractional Caputo-Riesz Diffusion Equations.
            <i>Numerical Mathematics: Theory, Methods and Applications</i>. <i>11</i> (4).
            827-853.
         doi:10.4208/nmtma.2018.s09