On a paper of Mazhar and Totik
A direct theorem for the approximation of continuous functions by modified Szász operators was given by \textit{S. M. Mazhar} and \textit{V. Totik} [ibid. 60, No. 2, 174-182 (1990; Zbl 0741.42001)]. Here this result is extended for combinations of these operators and an inverse theorem is proved. A connection between the behaviour of derivatives of these operators and the smoothness of functions is also considered.
scientific article; zbMATH DE number 205426