  The 818 fb^-1 dataset collected at the \psi(3770) resonance in the CLEO-c
detector offers unique possibilities for measuring strong-phase differences in
neutral D decays. We report results for D decays to K_S pi+ pi- and K_S K+ K-.
The measurements require that both D mesons in the event are fully
reconstructed, with one decaying to the signal mode of interest, and the other
to a CP-eigenstate, or a flavour-specific state, or K_{S,L} h+ h- (h = pi or
K). The strong-phase differences extracted from these decays are important
inputs to the determination of the CKM angle gamma with B->D(K_S h+ h-)K
decays.
