1. Barsky, B.A.: The ?-spline, a local representation based on shape parameters and fundamental geometric measures. Ph.D. dissertation, Dept. of Computer Science, University of Utah, Salt Lake City, Utah, 1981
2. Bohm, W., Farin, G., Kahmann, J.: A survey of curve and surface methods in CAGD. Computer Aided Geometric Design1, 1?60 (1984)
3. Dyn, N., Micchelli, C.A.: Shape preserving parametric representation of curves with local control for computer aided geometric design. IBM Research Report No. 10931, January 1985
4. Fritsch, F.N.: An annotated bibliography on the Fowler-Wilson spline. Preprint
5. Goodman, T.N.T.: Properties of ?-splines. Journal of Approximation Theory44, 132?153 (1985)