Eternal solutions to the Ricci flow

We consider solutions to the Ricci flow equation on a manifold X of dimension n . We say the solution is eternal if it is defined for all time -oo < t < oo. We are interested in solutions which are complete (which is a way of saying they are also defined for "all" of space) and which have their Riemannian curvature uniformly bounded for all space and time. This is a serious restriction; by the work of W. X. Shi [2] we know then that all the covariant derivatives of the curvature are bounded.