“…Then, from the Theorem 1.2, it follows that Equations (3.d) and (3.e) also hold on any 4-dimensional almost Hermitian manifold which is not necessarily compact. This answers affirmatively questions posed in [13,26]. In particular, if M = (M, g, J) is a 4-dimensional Kähler manifold one has the following curvature identities [13,26]:…”