[en] A three-level system for which one of the transitions from a common ground state is pumped by a strong biharmonic field, while the other transition is probed by a weak (mono- or bichromatic) field, is theoretically studied. The absorption spectrum of the probe field shows two types of parametric resonance: (1) resonances at the frequencies of ground-state splitting caused by the strong biharmonic field, (2) super-sharp resonances associated with undamped oscillations of the difference between level populations. 23 refs., 5 figs