1. Properties of Analytic Splines (1), Complex Polynomial Splines;Ahlberg;J. Math. Anal. Appl.,1969
2. Complex Cubic Splines;Ahlberg;Trans. Amer. Math. Soc.,1967
3. Best Approximation and Convergence Properties of Higher-Order Spline Approximations;Ahlberg;J. Math. Mech.,1965
4. The Theory of Splines and Their Applications;Ahlberg,1967
5. Interpolation and Approximation;Davis,1963