A class of integral operators preserving subordination and superordination for meromorphic functions

We denote by A the subclass of H a, 1 with the usual normalization f 0 f ′ 0 − 1 0, and denote by A the subclass ofA satisfying the condition h z h′ z / 0 for z ∈ U \ {0}. Let f and F be members of H. The function f is said to be subordinate to F, or F is said to be superordinate to f, if there exists a functionw analytic in Uwithw 0 0 and |w z | < 1 for z ∈ U and such that f z g w z z ∈ U . In such a case, we write