On calculation of effective galvanomagnetic characteristics of   inhomogeneous metals. Exact solution for the longitudinal effective   conductivity of polycrystals of metals in high magnetic fields
  In the framework of the perturbation theory an expression suitable for calculation of the effective conductivity of 3-D inhomogeneous metals in uniform magnetic field $H$ is derived. For polycrystals of metals with closed Fermi surfaces in high magnetic fields the perturbation series defining the longitudinal and the hall elements of the perturbation series can be summed allowing us to obtain the exact expression for the leading terms of all these elements of the effective conductivity tensor. 
Inna M. Kaganova, Moisey I. Kaganov