Universal Description of Granular Metals at Low Temperatures: Granular   Fermi Liquid
  We present a unified description of the low temperature phase of granular metals that reveals a striking generality of the low temperature behaviors. Our model explains the universality of the low-temperature conductivity that coincides exactly with that of the homogeneously disordered systems and enables a straightforward derivation of low temperature characteristics of disordered conductors. 
I.S. Beloborodov, A.V. Lopatin, and V.M. Vinokur