Spectral energy distributions of proto-GCs containing a cool SMS (blue lines show model A2 on the left, and model A4 on the right) plus a normal young stellar population (orange). The green curve indicates the nebular continuum emission from the young population. The total spectrum, also including nebular emission lines, is shown in red. The black curve shows a blackbody with the same T_eff and L as the SMS. The clear dominance of the SMS spectrum at wavelengths λ ≳ 3000 (1250) Å for model A2 (A4) is obvious.