Diffractive ηc photo-and electroproduction with the perturbative QCD Odderon J. Bartels, M.A. Braun, D. Colferai and G.P. Vacca Eur. Phys. J. C, 20 2 (2001) 323-331 Published online: 15 April 2001 DOI: 10.1007/s100520100676