Nonlinear optical responses due to exciton-phonon interactions in strongly coupled exciton-phonon systemsK.-D. Zhu, X.-Z. Yuan, J.-J. Dong and W.-S. LiEur. Phys. J. D, 30 1 (2004) 117-121DOI: https://doi.org/10.1140/epjd/e2004-00064-8