Duality between different mechanisms of QCD factorization in γ * γ collisions I. V. Anikin, I. O. Cherednikov, N. G. Stefanis and O. V. Teryaev Eur. Phys. J. C, 61 3 (2009) 357-367 Published online: 08 April 2009 DOI: 10.1140/epjc/s10052-009-1010-6