Variational method for the nonlinear dynamics of an elliptic magnetic stagnation lineA. H. Khater, D. K. Callebaut, M. A. Helal and A. R. SeadawyEur. Phys. J. D, 39 2 (2006) 237-245DOI: https://doi.org/10.1140/epjd/e2006-00093-3