“…In [19,20], it was established a relation of the generalized Moutard transformation for two-dimensional Dirac operators [21] to the conformal geometry of surfaces in three-and four-dimensional spaces, and with this were constructed blowing-up solutions of the modified Novikov-Veselov equation with regular initial data [22,23]. A generalization of the Moutard transformation to the case of generalized analytic functions, in particular, gave an approach to constructing the theory of generalized analytic functions with contour poles [24,25,26,27] and also allowed to construct a Moutard-type transformation for the conductivity equation [28].…”