An analytic function is quasi-subordinate to an analytic function , in the open unit disk if there exist analytic functions and , with , and such that . Certain subclasses of analytic univalent functions associated with quasi-subordination are defined and the bounds for the Fekete-Szegö coefficient functional for functions belonging to these subclasses are derived.
"Fekete-Szegö Problems for Quasi-Subordination Classes." Abstr. Appl. Anal. 2012 1 - 14, 2012. https://doi.org/10.1155/2012/192956