Gauge Independence and Relativistic Electron Dispersion Equation in   Dense Media
  We discuss the gauge parameter dependence of particle spectra in statistical quantum electrodynamics and conclude that the electron spectrum is gauge-parameter dependent. The physical spectrum being obtained in the Landau gauge, which leads to gauge invariance in a restricted class of gauge transformations. 
D. Oliva Ag\"uero, H. P\'erez Rojas, A. P\'erez Mart\'inez and A.   Am\'ezaga Hechavarr\'ia