“…Since V B − βI is a Fredholm operator with index 0 by Lemma 5, [17], Satz 51.8, Satz 51.1, the spectral radius of the operator V B − αI is smaller than |α|. Therefore there are constants d α ∈ 1, ∞), q α ∈ (0, 1) such that the relation (22) holds for each g ∈ B(∂G) and an integer number n. Since V is invertible in B there is a unique f ∈ B(∂G) such that V f = g for each g ∈ B(∂G). Easy calculation yields that f given by the series (23) fulfils V f = g.…”