1. L.Bittner, Ein Modell für eine Klasse von Aufgaben optimaler Steuerung. ZAMM 58 (1978), 251–260.
2. F.L. Chernousko, A.A.Lyubushin, Method of successive approximations for solution of optimal control problems. Optimal Control Appl. & Methods. Vol.3 (1982), 101–114.
3. P.N. Fedorenko, Approximative solution of optimal control problems (in Russian). Science. Moscow 1978.
4. W. Kampowsky, Optimal Control in Nonlinear Evolution Equations with Constraints. ZAMM 72 (1991) 7/8. 277–288.
5. J.A. Krylov, F.L. Chernousko, An Algorithm of successive approximations in control problems (in Russian). Jour. Num. Math./Math. Phys. 1962, 2, Nr.6, 1132–1139.