“…The continuing work of the authors mentioned explicitely in the above eventually culminated in, among other articles, a book by Ditzian and Totik [9], joint work of Ditzian and Zhou (see, e.g., [10]), an important article by Ditzian and Ivanov [8], a paper by Totik [36], and a significant contribution of Knoop and Zhou [23], [24]. A somewhat partial, but nonetheless streamlined, account of what had been achieved up to 1993, say, is given in the book of DeVore and Lorentz [5].…”