Perturbations in the Einstein theory of gravity: Conserved currents
  General relativity in the form where gravitational perturbations together with other physical fields propagate on an auxiliary background is considered. With using the Katz-Bi{\v{c}}\'ak-Lynden-Bell technique new conserved currents, divergences of antisymmetric tensor densities(superpotentials), in an arbitrary curved spacetime are constructed. 
A.N.Petrov