Before revision:  The proposed FD method has 2-\alpha order of accuracy with respect to time, where \alpha \in(0, 1) is the subdiffusion parameter, and 2 with respect to space . The paper is a continuation of 13 , where the derivation of the governing fractional differential equation, similarly as the stability and convergence analysis can be found .
After revision:  The proposed FD method has 2-\alpha order of accuracy with respect to time, where \alpha \in(0, 1) is the subdiffusion parameter, and 2 with respect to space 13 , where the derivation of the governing fractional differential equation, similarly as the stability and convergence analysis can be found .