“…Observe that, if we have (13) with γ < 0, [9, Theorem 1.2] is not true, because, from a mathematical point of view, [9, Lemma 2.6] does not hold (see also Lemmas 2.4,3.7. ) In this paper, we improve the result of [9], when γ > 0, assuming on the boundary datum (7).…”