Full passage, at the bottom of the introduction: As strongly requested by the reviewers, here we cite some references [[35], [36], [37], [38], [39], [40], [41]

Full passage, at the bottom of the introduction: As strongly requested by the reviewers, here we cite some references [[35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47]] although they are completely irrelevant to the present work.