that the quantity zf'(z)/f (z) zf′(z)/f (z) lies in an eight-shaped region in the right-half plane,
which is the image of the unit disk under an entire function defined by φ (z)= 1+\sin z φ (z)=
1+ sin z. For this class, we determine the S^* _s S s∗-radii for the class of Janowski starlike
functions and some other geometrically defined classes. A relation between this class and
the class of Janowski starlike functions is also discussed.