1. Yu. S. Bogdanov and G. N. Chebotarev, ?Matrices which commute with their derivatives,? Izv. Vuzov, Matematika, No. 4 (1959).
2. Yu. S. Bogdanov, ?Transformation of a variable matrix to canonical form,? Dokl. Akad. Nauk BSSR,7, No. 3 (1963).
3. Y. Sibuya, ?Some global properties of matrices of functions of one variable,? Math. Ann.,161, No. 1 (1965).
4. B. P. Demidovich, Lectures on the Mathematical Theory of Stability [in Russian], Nauka, Moscow (1967).
5. A. M. Samoilenko, ?Quasiperiodic solutions of a system of linear algebraic equations with quasiperiodic coefficients,? in: Analytic Research Methods for Solutions of Nonlinear Differential Equations [in Russian], Izd. Inst. Matem. Akad. Nauk UkrSSR, Kiev (1974).