E. Beltrami, Mathematics for Dynamic Modeling ( Academic Press, Boston, 1987); see section 6.2

J. Hale and H. Ko ak, Dynamics and Bifurcation ( Springer-Verlag, New York, 1991).

G. Iooss and D. D. Joseph, Elementary Stability and Bifurcation Theory ( Springer-Verlag, New York, 1980).

A. A. Andronov, E. A. Leontovich, I. I. Gordon, and A. G. Maier, Qualitative Theory of Second-Order Dynamic Systems ( Wiley, New York, 1973, Israel Program for Scientific Translations).

M. Braun, Differential Equations and Their Applications ( Springer-Verlag, New York, 1993, 4th edition); see Chapter 4.

L. Edelstein-Keshet, Mathematical Models in Biology ( McGraw-Hill, New York, 1988); see Chapter 5.

M. Humi and W. Miller, Second Course in Ordinary Differential Equations for Scientists and Engineers ( Springer-Verlag, New York, 1988); see Chapter 8.

D. A. McQuarrie, Mathematical Methods for Scientists and Engineers ( University Science Books; Sausalito, CA; 2003); see Chapter 13.

N. Minorsky, Nonlinear Oscillations ( Van Nostrand; Princeton, NJ; 1962); see Chapters 3 and 14.

V. V. Nemytskii and V. V. Stepanov, Qualitative Theory of Differential Equations ( Princeton University Press; Princeton, NJ; 1960); see pp. 133 134.

L. A. Segel, editor, Mathematical Models in Molecular and Cellular Biology ( Cambridge University...