Gravitational wave recoils in non-axisymmetric Robinson–Trautman spacetimes R. F. Aranha, I. Damião Soares and E. V. Tonini Eur. Phys. J. C, 74 10 (2014) 3097 Published online: 07 October 2014 DOI: 10.1140/epjc/s10052-014-3097-7