Stochastic multi-resonance in an overdamped bistable system with two types of modulation signal C. H. Zeng, A. L. Gong, C. P. Zeng and L. R. Nie Eur. Phys. J. D, 62 2 (2011) 219-225 Published online: 18 March 2011 DOI: 10.1140/epjd/e2011-10478-8