Luk'yanov, A.G., and Utkin, V.I., "Methods of Reducing Equations of Dynamic Systems to Regular Form", Automatic Remote Control, Vol. 42, No. 4, 1981, pp. 413-422.
Leal, Marco, Mendez, Andrea, Nixon, Quinton, Robbins, Christa, Fernandez, Luis, Rotating Pendulum Solution, Senior Design Project Report, Rice University, Houston, TX, 1997.