1. Bhatia, N. P. and Szegö, G. P.; Stability Theory of Dynamical Systems, Springer-Verlag, Berlin, 1970
2. Gottschalk, W. H. and Hedlund, G. A.; Topological Dynamics, Amer. Math. Soc. Coll. Publ., XXXVI, Amer. Math. Soc., Providence, R. I., 1955
3. Miller, R. K. and Sell, G. R.; Volterra Integral Equations and Topological Dynamics, Memoirs of the Amer. Math. Soc., 102, 1970
4. Nemytskii, v. v. and Stepanov, v. v.; Qualitative Theory of Differential Equations, (English tr.), Princeton Univ. Press., Princeton N. J., 1960
5. Zubov, V. I.; Methods of A. M. Lyapunov and Their Application, P. Noordhoff Ltd., The Netherlands, 1964