# Hokkaido Mathematical Journal

## Hokkaido Mathematical Journal, 36 (2007) pp.1-8

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### Abstract

By using the Ruscheweyh operator $D^n f(z)$, $z\in U$, we obtain sharp superordinations results related to some normalized holomorphic functions in the unit disk $U$.

MSC(Primary) 34A40 30C80, 30C45 differential subordination, differential superordination, univalent function