Elliptic flow at RHIC and LHC in the string percolation approach I. Bautista, J. Dias de Deus and C. Pajares Eur. Phys. J. C, 72 6 (2012) 2038 Published online: 14 June 2012 DOI: 10.1140/epjc/s10052-012-2038-6