Electromagnetic energy-momentum tensors in media
  It is pointed out that the previous energy-momentum tensors of Minkowski and Abraham for the electromagnetic field in continuous media are based on a covariant formulation which does not reflect a symmetry inherent to the system. Instead, taking into account the intrinsic invariance under Lorentz transformations involving the reduced speed of light in such a medium, a compact and fully consistent theory can be formulated without the old problems. 
Finn Ravndal