1. Antosiewicz, H. A., Rheinboldt, W. C.: Numerical analysis and functional analysis, chapter 14 of Survey of numerical analysis (J. Todd, Ed.). New York: McGrawHill 1962.
2. Bellman, R. E., Kalaba, R. E.: Quasilinearization and nonlinear boundary-value problems. New York: American Elsevier Publishing Co., Inc., 1965
3. Bosarge, W. E., Jr., Falb, P. L.: A multipoint method of third order. J. of Optimization Theory 4, 156–167 (1969).
4. Coddington, E. A., Levinson, N.: Theory of ordinary differential equations. New York: McGraw-Hill 1966.
5. Collatz, L.: Funktionalanalysis and Numerische Mathematik. Berlin- Göttingen-Heidelberg-New York: Springer 1964.