Locked and Unlocked Polygonal Chains in Three Dimensions.
Therese C. BiedlErik D. DemaineMartin L. DemaineSylvain LazardAnna LubiwJoseph O'RourkeMark H. OvermarsSteve RobbinsIleana StreinuGodfried T. ToussaintSue WhitesidesPublished in: Discret. Comput. Geom. (2001)