The purpose of this work is to obtain Jackson-type estimates in approximation by a complex Post-Widder operator in the unit disk. In addition, these operators preserve some sufficient conditions for starlikeness and univalence of analytic functions. © 2005 Elsevier Ltd. All rights reserved.
Anastassiou, G. A., & Gal, S. G. (2006). Geometric and approximation properties of a complex Post-Widder operator in the unit disk. Applied Mathematics Letters, 19(4), 314–319. https://doi.org/10.1016/j.aml.2005.04.012