“…The technique of calculations of this sort is given in Appendix A. In this way, we obtain (see [31] , which corresponds to the trimming of the integrals in the impulse space by definition of the parameters ij [26,36]. If the interband interaction is neglected, what can be done when 11 , 22 >> 12 , 21 , then on the basis of (3.9) and (3.10) we shall obtain two independent equations, from which it follows that, at 0 , * 1 (x) does not depend on the magnetic field value.…”