1. Tinkertoy is a trade-mark of Playskool, Inc., Pawtucket, RI 02862, used to designate a children’s toy construction set consisting of straight beams and connectors.
2. Lego is the trade-mark of LEGO System A/S, DK-7190 Billund, Denmark, and designates a children’s toy construction set.
3. Feynman, R. P. Saturday Review 1960, 43, April 2, 45.
4. Hameroff, S. R. Ultimate Computing. Biomolecular Consciousness and NanoTechnology; North Holland, Amsterdam, 1987; Chapter 10.
5. Wiberg, K. B.; Waddell, S. T.; Laidig, K. Tetrahedron Lett. 1986, 27, 1553.