1. A Course in Approximation Theory;Cheney,2000
2. Multivariate Splines;Chui,1988
3. Splines as linear combinations of B-splines, a survey;de Boor,1976
4. A Practical Guide to Splines;de Boor,2001
5. Quasi interpolants and approximation power of multivariate splines;de Boor,1990