  In this paper, we are concerned with complex Ginzburg-Landau (CGL) equations.
There are several results on the global existence and smoothing effects of
solutions to the initial boundary value problem for (CGL) in bounded or
unbounded domains. In this paper, we study the time periodic problem for (CGL)
in bounded domains. The main strategy in this paper is to regard (CGL) as a
parabolic equation with monotone and non-monotone perturbations and to apply
non-monotone perturbation theory of parabolic equations developed by Otani
(1984).
