[1] M. Vidyasagar, “Nonlinear Systems Analysis”, Prentice Hall, 2’nd Ed, 1993.
[2] H. K. Khalil, “Nonlinear systems”, Prentice Hall, Englewood Cliffs, NJ, Third ed., 2002.
[3] K.S Narendra, and A.M. Annaswamy, “Persistent excitation in adaptive systems”, Internat. J. Control, vol. 45, pp. 127-160, 1987.
[4] D. Aeyels and J. Peuteman, “A new asymptotic stability criterion for nonlinear time-variant differential equations”, IEEE Trans. Automat. Control, vol. 43, pp. 968-971, 1998.
[5] R. Bellman, “Vector Lyapunov functions,” SIAM J. Control, vol. 1, pp. 32–34, 1962.
[6] V. M. Matrosov, “Method of vector Liapunov functions of interconnected systems with distributed parameters (survey)” (in Russian), Avtomatika i Telemekhanika, vol. 33, pp. 63–75, 1972.
[7] A.A. Martynyuk, “Stability analysis by comparison technique”, Nonlinear Analysis 62 (2005) 629-641.
[8] S. G. Nersesov, W.M. Haddad, “On the stability and control of nonlinear dynamical systems via vector Lyapunov functions”, IEEE Transaction on Automatic Control, vol. 51, no. 2, 2006.
[9] M. B. Kudaev, “A study of the behavior of the trajectories of systems of differential equations by means of Lyapunov functions”, Dokl. Akad. Nauk. SSSR 147, pp. 1285-1287, 1962.
J. A. Yorke, “A theorem on Liapunov functions using ϋ”, Theory of Computing Systems, Springer, vol. 4, no 1, p