$\mathcal{O}(m{\alpha }^2(Z\alpha {)}^6)$ contribution to Lamb shift from radiative corrections to the Wichmann-Kroll potential

We derive an analytical expression for the contribution of the order $m{\alpha }^2(Z\alpha {)}^6$ to the hydrogen Lamb shift which comes from the diagrams for radiative corrections to the Wichmann-Kroll potential. We use modern methods of multiloop calculations, based on IBP reduction, DRA method and differential equations.