Effect of gap opening on the quasiparticle properties of doped graphene sheets A. Qaiumzadeh, F. K. Joibari and R. Asgari Eur. Phys. J. B, 74 4 (2010) 479-485 Published online: 13 April 2010 DOI: 10.1140/epjb/e2010-00125-3