1. Beech, R. (2001). The Practical Illustrated Encyclopedia of Origami. The Complete Guide to the art of paper folding. Lorenz Books.
2. Lang, R.J. (1988). The Complete Book of Origami. Step by step Instructions in Over 1000 Diagrams. New York: Dover Publications Inc,. http://www.langorigami.com/art/science/science.php4 http://www.langorigami.com/art/artmain/artmain.php4.