Parity nonconserving two-pion exchange in elastic proton-proton scattering J. A. Niskanen, T. M. Partanen and M. J. Iqbal Eur. Phys. J. A, 36 3 (2008) 295-301 Published online: 10 June 2008 DOI: 10.1140/epja/i2007-10595-x