Proof of factorization for electroproduction of multiple mesons and exclusive $γ^* γ$ production of multiple hadrons

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.