  In [3], the authors proved that uniqueness holds among solutions whose
exponentials are $L^p$ with $p$ bigger than a constant $\gamma$
($p\textgreater{}\gamma$). In this paper, we consider the critical case:
$p=\gamma$. We prove that the uniqueness holds among solutions whose
exponentials are $L^\gamma$ under the additional assumption that the generator
is strongly convex.
