“…In many papers, the results concerning essential norms are given in terms of "almost" equalities, not "exact" equalities. See, for example, [18,19,22,23]. It is worth mentioning here that the results of Theorems 3.1,3.2,and 3.3 and Corollary 3.4 are given in terms of "exact" equalities, not "almost" equalities.…”