“…The proof in [1, Lemma C.2] (for n = 3, m > 0, s = 1/2) uses the explicit expression for the Green's function for n = 3 [4, (IX.30)]. We give a modified proof, which holds for all n ≥ 1, and m > 0, s ∈ (0, 1), as well as s = 1/2, m = 0, referring to [1] for further details. We start with m > 0, s ∈ (0, 1).…”