1. D. U. von Rosenberg,Methods for the Numerical Solutions of Partial Differential Equations, American Elsevier Publishing Company, Inc., New York, 1969.
2. S. K. Godunov andV. S. Ryabenki,Theory of Difference Schemes, John Wiley and Sons, Inc., New York, 1964.
3. F. Angel, «Invariant Imbedding, Difference Equations, and Elliptic Boundary Value Problems», USCEE Technical Report 69-16, October 1969.
4. H. Kagiwada andR. Kalaba, «Deviation and Validation of an Initial-Value Method for Certain Nonlinear Two-Point Boundary Value Problems».Journal of Optimization Theory and Applications, v. 2, No. 6, 378–385, Nov. 1968.
5. R. Bellman, H. Kagiwada andR. Kalaba, «Invariant Imbedding and a Reformulation of the Internal Intensity Problem in Transport Theory»,Monthly Notices of the Royal Astronomical Society v. 132, 183–191, 1966.