Weakly nonlinear analysis on the Kelvin-Helmholtz instability L. F. Wang, W. H. Ye, Z. F. Fan, Y. J. Li, X. T. He and M. Y. Yu EPL, 86 1 (2009) 15002 Published online: 15 April 2009 DOI: 10.1209/0295-5075/86/15002