. For and . Mainly, Spirographe_(jeu) Osaka museum: http://fr.wikipedia.org/wiki/Fenêtre_de_Viviani "Ovales de Cassini" : picture from G. Lachaud "Cassini statue": http: //home.nordnet.fr/~ajuhel/Obs_Paris/Cassini/cassini.html The eightfold way. The beauty of Klein's quartic curve, Mathematical Sciences Research Institute Publications, pp.35-325, 1999.