1. J. Banks, J. Brooks, G. Cairns, G. Davis and P. Stacey, “On Devaney’s definition of Chaos”, Am. Math. Monthly
99 (1991), pp. 332–334.
2. R. L. Devaney, An Introduction to Chaotic Dynamical Systems, 2nd-ed., Addison-Wesley, Redwood City, CA., 1989.
3. V.V. Nemytskii and V.V. Stepanov, Qualitative Theory of Ordinary Differential Equations, Princeton Univ. Press, Princeton, 1960.