Energy-preserving Runge-Kutta methods Elena Celledoni, Robert I. McLachlan, David I. McLaren, Brynjulf Owren, G. Reinout W. Quispel and William M. Wright ESAIM: M2AN, 43 4 (2009) 645-649 Published online: 08 July 2009 DOI: 10.1051/m2an/2009020