Dj. Needham, A CENTER THEOREM FOR 2-DIMENSIONAL COMPLEX HOLOMORPHIC SYSTEMS AND ITS GENERALIZATION, Proceedings - Royal Society. Mathematical and physical sciences, 450(1939), 1995, pp. 225-232
We consider a two-dimensional complex holomorphic system. In particula
r, we use the centre manifold theory together with the singular point
theory of C. H. Briot & J. C. Bouquet (J. Ec. imp. Polyt. 21. 133 (185
6)) to establish a centre theorem concerning the behaviour of the phas
e paths of the system in the neighbourhood of an equilibrium point hav
ing a single purely imaginary eigenvalue. An extended centre theorem i
s established for the corresponding N-dimensional complex holomorphic
system (N greater than or equal to 3).