1. Fuhs, W., Stachel, H.: Circular pipe-connections. Comput. Graph. 12(1), 53–57 (1988)
2. Zawidzki, M., Nishinari, K.: Modular pipe-z system for three-dimensional knots. J. Geom. Graph. 17(1), 81–87 (2013)
3. Zawidzki, M., Nagakura, T.: Arm-Z: a modular virtual manipulative. In: Schröcker, H-P. (ed.) Proceedings of the 16th International Conference on Geometry and Graphics, pp. 75–80 (2014)
4. Gray, J.: The mechanism of locomotion in snakes. J. Exp. Biol. 23(2), 101–120 (1946)
5. Hirose, S.: Biologically Inspired Robots: Snake-Like Locomotors and Manipulators. Oxford University Press, Oxford (1993)