1. Making stepper motors behave;Harned;Machine Design,1985
2. Singular perturbation in piecewise-linear systems;Heck,1988
3. Extensions of singular perturbation analysis in piecewise-linear systems;Heck,1988
4. Controllability and time-optimal control of systems with slow and fast modes;Kokotovic;IEEE Trans. Aut. Control,1975