  In the following, we will present a generalization of the proof of
factorization for electroproduction of vector mesons to the production of
several mesons such as $\pi^+\pi^-$ and a proof of factorization for exclusive
$\gamma^* \gamma$ production of several hadrons for example $p \bar p$ or
$\pi^+\pi^-$ to all orders in perturbation theory up to power suppressed terms.
