QSO size ratios from multiband monitoring of a microlensing high-magnification event L. J. Goicoechea, V. Shalyapin, J. González-Cadelo and A. Oscoz A&A, 425 2 (2004) 475-487 Published online: 21 September 2004 DOI: 10.1051/0004-6361:20047156