  We report a theoretical description of far-infrared spectroscopy experiments
on self-assembled quantum rings in a magnetic field [A. Lorke et al., Phys.
Rev. Lett. 84, 2223 (2000)] which, for the first time, accounts for the full
set of experimental resonances. In our calculations we use a 3D effective-mass
model with a realistic finite step-like confinement potential, including strain
and Coulomb effects. We assume a bimodal distribution of ring sizes.
