pendule de Wilberforce

[1990] Wilberforce's pendulum revisited ; Ulrich Köpf ; American Journal of Physics 58 (sep 1990) p. 833 [lien]
[1991] Wilberforce pendulum oscillations and normal modes ; Richard E. Berg ; Todd S. Marshall ; American Journal of Physics 59 (jan 1991) p. 32 [lien]