“…The first results of this kind we proved by Kokilashvili, Samko and their collaborators [25,40,41,42,43]; these results were more recently extended to classes of weights who oscillate between powers: see [1,21,22,23,24,26,27,37,38]. Other results in this direction have been proved by a number of authors; see, for example, [4,3,15,20,32,33].…”