1. Wylie, C. P., Advanced Engineering Mathematics, McGraw-Hill Book Company, Inc., New York, N.Y. 175–178 (1967).
2. Ahlberg, J. H., Nilson, E. N. andWalsh, J. L.:The Theory of Splines and their Applications, Academic Press, New York, N.Y., 1, 2. 9–16 (1967).
3. Ibid,.109, 110.
4. Reinsch, C. H., “Smoothing by Spline Functions”,Numerische Mathematik,10,177–183 (1967).
5. Franklin, P., Methods of Advanced Calculus, McGraw-Hill Book Co., Inc., New York, N.Y., 432–437 (1959).