“…Since f is a global analytic first integral of system (13), f (x, y, z, 0, v) is a global analytic first integral of system (9). So we are in the assumptions of Lemma 9, applying it we get that f (x, y, z, 0, v) = T (v), that is, T is a global analytic function of v. Therefore using the convergent power expansion series of f (x, y, z, h, v) in a neighborhood of the origin (0, 0, 0, 0, 0) we can write f (x, y, z, h, v) = T (v) + hg, where g = g(x, y, z, h, v) is a convergent power series in a neighborhood of (0, 0, 0, 0, 0).…”