Intergalactic HeII absorption towards QSO 1157+3143 D. Reimers, C. Fechner, H.-J. Hagen, P. Jakobsen, D. Tytler and D. Kirkman A&A, 442 1 (2005) 63-68 Published online: 30 September 2005 DOI: 10.1051/0004-6361:20053365