On [3, p. 199] one says "We mention parenthetically that the proof of [99,
Lemma 41.3] is incorrect, and we do not know whether it, [99, Theorem 41.5] and
[99, Theorem 41.6] are true". The previously cited reference [99] is our
reference [2]. The aim of this short note is to provide a result that improves
upon [2, Lemma 41. 3].