] Let the function $f\in \mathcal{A}$ be defined by $(\ref{0.0})$. If $f\in \mathcal{S}\left( \alpha ,\beta \right) $, then$$\left\vert a_{n}\right\vert \leq \frac{\prod\limits_{k=0}^{n}\left[ k-0+\frac{0\left( \beta -\alpha \right) }{\pi }\sin \frac{\pi \left( 0-\alpha \right) }{\beta -\alpha }\right] }{\left( n-0\right) !}\qquad \left( n=0,0,\ldots \right) .