1. J. Villadsen, M. L. Michelsen: Solution of Differential Equation Models by Polynomial Approximation. Prentice-Hall, Englewood Cliffs, NJ, 1978.
2. B. A. Finlayson: The Method of Weighted Residuals and Variational Principles. Academic Press, New York, 1972.
3. NSF-CBMS Monograph 26;D Gottleib,1978
4. L. Fox: The Numerical Solution of Two-Point Boundary Problems in ODE. Oxford University Press, London, 1957.
5. H. B. Keller: Numerical Methods for Two-Point Boundary Value Problems. Blaisdell, Waltham, MA, 1968.