  We consider application of the multiple time delayed feedback for control of
anharmonic (nonlinear) oscillators subject to noise. In contrast to the case of
a single delay feedback, the multiple one exhibits resonances between feedback
and nonlinear harmonics, leading to a resonantly strong or weak oscillation
coherence even for a small anharmonicity. Analytical results are confirmed
numerically for van der Pol and van der Pol-Duffing oscillators.
  Highlights: > We construct general theory of noisy limit-cycle oscillators
with linear feedback. > We focus on coherence and "reliability" of oscillators.
> For recursive delay feedback control the theory shows importance of
anharmonicity. > Anharmonic resonances are studied both numerically and
analytically.
