Zicheng Liu and Michael F. Cohen, Keyframe Motion Optimization By Relaxing Speed and Timing, Computer Animation  and Simulation'95, D. Terzopoulos and D. Thalmann(eds.).

 

Zicheng Liu and Michael F. Cohen,  Efficient symbolic interface for constraint based animation system,    Computer Animation and Simulation'95, D. Terzopoulos and D. Thalmann(eds.).

 

Zicheng Liu and Michael F. Cohen, Decomposition of Linked Figure Motion: Diving, Proceedings of the 5th  EuroGraphics Workshop on Simulation and Animation, 1994.

 

Zicheng Liu, Steven J. Gortler and Michael F. Cohen,  Hierarchical Spacetime Control, SIGGRAPH94 (Computer Graphics, Vol 28, No 7).

 

Zicheng Liu,  Efficient Animation Techniques Balancing Both User Control and Physical realism, PhD thesis, Princeton University, 1996.