References
14.1 Matthews, M R, Gauld C F and Stinner, A, (2005), The Pendulum: Scientific, Historical, Philosophical and Educational Perspectives, pp. 37-47, Springer Netherlands, Dordrecht, ISBN 978-1-4020 3525 8.
14.2 Zou, D and Ji, T, (2008), Dynamic characteristics of a generalised suspension system, International Journal of Mechanical Sciences, Vol. 50, pp. 30-42.