Observational determination of the time delays in gravitational lens system Q2237+0305 V. Vakulik, R. Schild, V. Dudinov, S. Nuritdinov, V. Tsvetkova, O. Burkhonov and T. Akhunov A&A, 447 3 (2006) 905-913 Published online: 10 February 2006 DOI: 10.1051/0004-6361:20053574