  The estimates for the second Hankel determinant a_2a_4-a_3^2 of analytic
function f(z)=z+a_2 z^2+a_3 z^3+...b for which either zf'(z)/f(z) or
1+zf"(z)/f'(z) is subordinate to certain analytic function are investigated.
The estimates for the Hankel determinant for two other classes are also
obtained. In particular, the estimates for the Hankel determinant of strongly
starlike, parabolic starlike, lemniscate starlike functions are obtained.
