1. G. Scharf:Nuovo Cimento A,74, 302 (1983).
2. K. Yajima:J. Fac. Sci. Univ. Tokyo, Sect. 1A,29, 161 (1982).
3. R. Courant andD. Hilbert:Methoden der Mathematischen Physik II (Berlin, Heidelberg, New York, N.Y., 1968).
4. P. Hartman:Ordinary Differential Equations (New, York N.Y., London, Sydney, 1964).
5. P. Hartman (4),Ordinary Differential Equations (New, York N. Y., London, Sydney, 1964), Theorem 6.2, p. 243. ForC m-case, see Exercise 5.1(b), p. 238.