1. A.B. Antonevich: Linear Functional Equations ? The Operator Theory Approach. University Press, Minsk 1988 [Russian].
2. R.B. Burckel: An Introduction to Classical Complex Analysis, Vol. 1. Birkhäuser Verlag, Basel and Stuttgart 1979.
3. C.C. Cowen: Composition operators on Hilbert spaces of analytic functions ? a status report. In: Proc. Symp. Pure Math., Vol. 51, Part 1, pp. 131?145, Amer. Math. Soc., Providence, RI, 1990.
4. F. Harary: Graph Theory. Addison-Wesley Publ. Comp. 1969.
5. M. Klin, R. Pöschel, K. Rosenbaum: Angewandte Algebra. Deutscher Verlag der Wissenschaften, Berlin 1988.