A general nonlinear Fokker-Planck equation and its associated entropy V. Schwämmle, E. M.F. Curado and F. D. Nobre Eur. Phys. J. B, 58 2 (2007) 159-165 Published online: 10 August 2007 DOI: 10.1140/epjb/e2007-00217-1