An optical time delay for the double gravitational lens system FBQ 0951+2635 P. Jakobsson, J. Hjorth, I. Burud, G. Letawe, C. Lidman and F. Courbin A&A, 431 1 (2005) 103-109 Published online: 02 February 2005 DOI: 10.1051/0004-6361:20041432