Campbell,S. A. and Belair, J., 1992, “Multiple-delayed differential equations as model for biological control systems.” In Proceeding World Congress of Nonlinear Analysts’ 92, 3110-3117 ,Tampa.
 Kim, J.-H., 2001, “Delay and Time-Derivative Dependent Robust Stability of Time-Delay Linear Systems with Uncertainty.” IEEE Trans. Autom. contr., 46,(5), 789-792.
 Kuang, Y., 1993, Delay Differential Equations with Applications in Population Dynamics. Academic Press, Boston. 9
 Li, C. D. and Liao, X. f., 2006, “A global exponential robust stability criterion for NN with variable delays.” Neurocomputating 69, 80-89.
 Li, X. and de Souza, C. E., 1995 “LMI approach to delay -dependent robust stability of uncertain linear systems.” in Proc. of the 34th CDC, New Orleans, 3614-3619.
 Li, X. and de Souza, C. E., 1997, “Delay dependent robust
stability and stabilization of uncertain linear delay system: A linear Matrix Inequality Approach.” IEEE Trans. on Automatic
Control, 42, 1144-1148.
 Macdoonald, N., 1989, Biological Delay Systems: Linear Stability Theory, CambridgeUniversity Press, Cambridge.
 Niculescu, S.-I., Doin, J.-M., Dugard, L., and Li, H., 1997, “Stability of linear systems with several delays: An L.M.I. approach.” JESA, special issue on ‘Analysis and control of time-delay systems’ 31, 955-970.
 Niculescu, S.-I., 2001, Delay effects on stability: A robust
approach. Springer, Berlin.
 Stepan, G., 1998, “Retarded dynamical system stability and characteristic function.” Research Notes in Mathematics Series, John Wiley, New York, P:210.
 Su, J .H., 1994, “Further results on the robust stability of linear systems with a single delay.” Systems and Control Letters, 23, 375-379.
 Zhang, Z., Liao, and Ch. Li, X., 2006, “Delay-dependent robust stability analysis for interval linear time-variant system with delays and application to delayed neural networks.” Neurocomputating, doi:10.1016/j.neucom.2006.09.010, .