1. Matsuda R&D co., LTD: Shock absorber (metal ball) (in Japanese). http://www.mrd-matsuda.co.jp/airsus_ metal.html.
2. Born, M.: Untersuchungen über die Stabilität der elastischen Linie in Ebene und Raum: unter verschiedenen Grenzbedingungen (Ph.D. thesis), University of Göttingen. (1906)
3. Bisshopp, K.E., Drucker, D.C.: Large deflection of cantilever beams. Q. Appl. Math. 3(3), 272–275 (1945)
4. Frish-Fay, R.: Flexible bars. Butterworths, London (1962)
5. Shoup, T.E., McLarnan, C.W.: On the use of the undulating elastica for the analysis of flexible link mechanisms. ASME J. Eng. Ind. 93, 263–267 (1971)