Photon polarization in the two-photon decay of heavy hydrogen-like ions A. Surzhykov, T. Radtke, P. Indelicato and S. Fritzsche Eur. Phys. J. Special Topics, 169 (2009) 29-34 Published online: 17 March 2009 DOI: 10.1140/epjst/e2009-00969-8