Diffractive ηc photo-and electroproduction with the perturbative QCD Odderon J. Bartels, M.A. Braun, D. Colferai and G.P. VaccaEur. Phys. J. C, 20 2 (2001) 323-331DOI: https://doi.org/epjc/v20/p323(epjc0676)