The Sylow Theorems · Challenge problem

A group $G$ has order $99=3^2\cdot11$. Using Sylow III, both its Sylow $3$-subgroup (order $9$) and Sylow $11$-subgroup (order $11$) are forced to be normal, so $G$ is the direct product of the two. How many groups of order $99$ are there, up to isomorphism?