1. Zuppinger H. Die active flexion im unbelasteten kniegelenk, Zuricher Habil. Wiesbaden, Bergmann 1904; 703–763
2. Kapandji IA. The physiology of the joints. In: Lower limb, Vol 2, London and Edinburgh: Churchill Livingstone, p. 120
3. The mechanics of the knee and prosthesis design;Goodfellow;J Bone Joint Surg (Br),1978
4. Geometry of the knee;O'Connor,1990
5. Lehrbuch der muskel und gelenkmechanik, III;Strasser,1917