Duality considerations about the Maxwell-Podolsky theory through the   symplectic embedding formalism and spectrum analysis
  We find the dual equivalent (gauge invariant) version of the Maxwell theory in D=4 with a Proca-like mass term by using the symplectic embedding method. The dual theory obtained (Maxwell-Podolsky) includes a higher-order derivative term and preserve the gauge symmetry. We also furnish an investigation of the pole structure of the vector propagator by the residue matrix which considers the eventual existence of the negative-norm of the theory. 
E. M. C. Abreu, A. C. R. Mendes, C. Neves, W. Oliveira, C. Wotzasek   and L. M. V. Xavier