1. H. Haken: Z. Naturforsch. 8A, 228 (1954)
2. H. Haken: In Dynamics of Synergetic Systems, Springer Ser. Synergetics, Vol. 6, ed. by H. Haken (Springer, Berlin, Heidelberg, New York 1980) p. 16
3. For the proof of Theorem 3.8.2 I used auxiliary theorems represented in N. Dunford, J. T. Schwartz: Linear Operators, Pure and Applied Mathematics, Vol. VII, Parts I-III (Wiley, Interscience, New York 1957)
4. N. N. Bogoliubov, I. A. Mitropolskii, A. M. Samoilento: Methods of Accelerated Convergence in
5. Nonlinear Mechanics (Springer, Berlin, Heidelberg, New York 1976)