be observed only for temperature pretty close to $T_0$, certainly not far away from $T_0$ than $\simeq 0.01\hskip2pt T_0$. To perform the measurements while keeping the temperature constant with high accuracy is a major obstacle for the experimental test of the theory (especially taking into account the possible mesoscopic inhomogeneity of the amorphous sample leading to some variation of $T_0$ across the sample). Transition to the anomalous diffusion could occur at the temperature significantly higher than $T_0$, thus providing, in this respect, a less demanding method to test the effects of spatial correlation. At the same time, a very essence of the suggested method requires to work with several experimental samples having different thickness of the transport layer. There is a pressing need to keep the structure of different samples as close as possible, again avoiding mesoscopic inhomogeneities in order to provide a reliable comparison.

At last, we should note that in this paper we consider the behavior of $D$ in the infinite medium. Possible experimental tests are directly related to the finite thickness of transport layers and, hence, the drift time should be much greater than the time of the formation of the final well-developed anomalous diffusion regime. Typical 