For a normalized analytic function defined on the unit disc , let be a function of positive real part in , need not have that property in , and . For certain choices of and , a sharp radius constant is determined, , so that maps onto a specified region in the right half-plane.
"On the Largest Disc Mapped by Sum of Convex and Starlike Functions." Abstr. Appl. Anal. 2013 1 - 12, 2013. https://doi.org/10.1155/2013/682413