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2. On the construction of monotony preserving taper curves;Lahtinen;Acta For. Fennica,1988
3. Shape preserving interpolation by quadratic splines;Lahtinen;J. Comput. Appl. Math.,1990
4. An algorithm for computing a shape-preserving osculatory quadratic spline;McAllister;ACM Trans. Math. Software,1981
5. Results and problems in shape preserving interpolation and approximation with polynomial splines;Schmidt,1989