Quotient Equations and Integrals of Motion for Vector Massless Field
  In this article a group-theoretical aspect of the method of dimensional reduction is presented. Then, on the base of symmetry analysis of an anisotropic space geometrical description of dimensional reduction of equations for vector massless field is given. Formula for calculating components of the energy-momentum tensor from the variables of the field factor-equations is derived. 
S. S. Moskaliuk