1. R. Courant, D. Hilbert, Methods of Mathematical Physics, Vol I, WileyInterscience, New York, 1968.
2. F.R. Gantmacher, Applications of the Theory of Matrices, Wiley-Interscience, New York, 1959.
3. E.W. Cheney, D. Kincaid, Numerical Mathematics and Computing, Brooks-Cole, Monterey, CA, 1980.
4. M.M. Vainberg, V.A. Trenogin, Theory of Branching of Solutions of Nonlinear Equations, Noordhoff, Leyden, 1974.
5. E. Hille, Analytic Function Theory, Vol. 1 and 2, Ginn, New York, 1959.