delta-doped layer and thus the asymptotic of the wave functions was similar to 3D. The important result of theory suggested in [5] was the following: the patterns of the negative magnetoresistance were almost universal predicting the maximum value of ∼ 0 . 6 of the total resistance, and even the combination of the negative magnetoresistanse and positive wave-shrinkage magnetoresistance gave the maximum value of negative peak (with respect to average resistance) of around 40 percents. Unfortunately, these predictions for ”strong scattering case” were not in a good agreement with experiment. First, in most of experimental studies the effect of negative magnetore- sistance have not exceeded 10 percents and typically was around several percents. Then, it was shown [6] that in 3D semiconductors the negative magnetoresistance is suppressed with a decrease of temperature after the crossover from Mott-type hopping (at higher tempera- tures) to Efros-Shklovskii hopping over the states within the Coulomb gap. In the paper [6] we explained such a behavior as a result of a decrease of concentration of the scattering centers within the Coulomb gap. However our calculations were based on the assumption that the preexponential factor of the wave functions asymptotic corresponded to scattering states of [2] (”weak scattering case”) rather than to hydrogen-like asymptotics exploited in [5]. Later [7] we have also demonstrated that to fit the experimental data one should also take into account spin mechanisms of magnetoresistance. The first one, considered in [8], is based on the fact that the intermediate scatterer should be occupied to produce a negative scattering amplitude. Thus the interference depends on the mutual orientation of the spin of the hopping electron and of the spin of scattering center. Without external magnetic field only one half of the configurations gives an interference. In magnetic field all localized spins are aligned which increases the role of interference and, correspondingly, leads to an increase of resistance. Another spin mechanism of positive magnetoresistance was first considered in Ref. [9] and then was studied in detail in [10]. It is related to a presence of doubly-occupied hopping sites (corresponding to the upper Hubbard band). Due to spin correlations on these sites requiring s-pairing of the spins (recall that we consider here electron rather than hole hopping) some hopping transitions are suppressed in magnetic field (like ones from single-occupied site to single-occupied site). As it was mentioned above, the incorporation of all of the relevant factors allowed us to reach a quantitative agreement between the theoretical model and experimental data. 3