1. V. I. Arnol'd, ?On matrices that depend on parameters,?Usp. Mat. Nauk,26, No. 2, 101?114 (1971).
2. V. I. Arnol'd, ?Lectures on bifurcations and versal families,?Usp. Mat. Nauk,27, No. 5, 119?184 (1972).
3. V. I. Arnol'd,Supplementary Chapters in the Theory of Ordinary Differential Equations [in Russian], Nauka, Moscow (1978).
4. D. M. Galin, ?On real matrices depending on parameters,?Usp. Mat. Nauk,27, No. 1, 241?242 (1972).
5. J. Williamson. ?On the algebraic problem concerning the normal forms of linear dynamical systems,?Amer. J. Math.,58, No. 1, 141?163 (1936).