SUSSMANN, H. Controllability of Nonlinear Systems. J. Differential Equations. 1972, 12, 95-116
TSINIAS, J. Transforming a Controllable Multiinput Nonlinear System to a Single Input Controllable System by Feedback. System & Control Letters. 1981, 1, 3, 173-178
BYRNES, C. I. Asymptotic Expansions, Rootloci and Global Stability, Algebraic and Geometric Methods in Nonlinear Control Theory. 1986, 159-179