A nonextensive approach to the dynamics of financial observables S. M.D. Queirós, L. G. Moyano, J. de Souza and C. Tsallis Eur. Phys. J. B, 55 2 (2007) 161-167 Published online: 01 June 2006 DOI: 10.1140/epjb/e2006-00205-y