Frequency Domain Stability Criteria-Part I

[1]  Paul Slepian,et al.  Positive Real Matrices , 1960 .

[2]  J. P. Lasalle Some Extensions of Liapunov's Second Method , 1960 .

[3]  R. W. Brockett,et al.  On the Stability of Nonlinear Feedback Systems , 1964, IEEE Transactions on Applications and Industry.