On non-perturbative Anderson localization for C^\alpha potentials   generated by shifts and skew-shifts
  In this paper we address the question of proving Anderson localization (AL) for the operator [H(x,\omega)\psi](n) := - \vp(n+1) - \vp(n-1) + V\bigl(T^n_\omega x\bigr)\psi(n), n\in\mathbb Z where T:\tor^2\to\tor^2 is either the shift or the skew-shift and V is only C^\alpha(\tor^2) for some \alpha>0. We show that under the assumption of positive Lyapunov exponents, (AL) takes place for a.e. frequency, phase, and energy. 
Jackson Chan, Michael Goldstein, Wilhelm Schlag