On coefficient inequalities of certain subclasses of bi-univalent functions involving the S?l?gean operator

In the present investigation, with motivation from pioneering work of Srivastava et al. [28], which in recent years actually revived study analytic and bi-univalent functions, we introduce subclasses T*?(n,?) T?(n,?) function class ? defined open unit disk U = {z C : |z| < 1g involving S?l?gean derivative operator Dn. Moreover, derive estimates on initial coefficients |a2| |a3| for functions these pointed out connections some earlier known results.