CLEO-c inputs to the determination of the CKM angle gamma

The strong-phase differences between D0 and D0bar decays to common final states are crucial parameters in the determination of the CKM angle gamma from B to DK modes. The first quantum-correlated measurements of these parameters in several D decay modes have been performed with the CLEO-c data at the psi(3770) resonance. Studies for D to K0 K+ K-, D to K0 pi+ pi-, D to K+ pi-, D to K+ pi- pi0, and D to K+ pi- pi+ pi- are reviewed.