“…Moreover, in that case, we do not need (6) to prove the previous theorem, since then (α − A) (α − A) −1 = 1, α ∈ ρ(A), and A t,i are single-valued, whenever 0 < t < 1 and i = 1, 2. Thus, the preceding theorem admits a simpler formulation for single-valued operators.…”