1. H. Bohr, Almost-Periodic Functions (Chelsea Publishing Company, New York, NY, 1947; URSS,Moscow, 2009).
2. B. M. Levitan and V. V. Zhikov, Almost-Periodic Functions and Differential Equations (Izd. Moskov. Univ.,Moscow, 1978; Cambridge University Press, Cambridge–New York, 1982).
3. L. S. Pontryagin, Continuous Groups, 3rd ed. (Nauka, Moscow, 1973; Topological Groups, transl. of the 2nd ed., Gordon and Breach Science Publishers, Inc., New York–London–Paris, 1966).
4. W. Rudin, Fourier Analysis on Groups (Intersience Publ., New York, 1962).
5. A. Katok and B. Hasselblatt, Introduction to the Modern Theory of Dynamical Systems (Cambridge University Press, Cambridge, 1995; Faktorial,Moscow, 1999).