Two-loop self-energy correction to the ground-state Lamb shift in H-like   ions
  The two-loop self-energy correction is evaluated to all orders in Z alpha for the ground-state Lamb shift of H-like ions with Z >= 20, where Z is the nuclear charge number and alpha is the fine structure constant. The results obtained are compared with analytical calculations performed within the Z alpha expansion. 
V. A. Yerokhin, P. Indelicato, and V. M. Shabaev