Thomas W. Sederberg David L. Cardon G. Thomas Finnigan Nicholas S. North Jianmin Zheng Tom Lyche T-spline simplification and local refinement. 276-283 2004 23 ACM Trans. Graph. 3 http://doi.acm.org/10.1145/1015706.1015715 db/journals/tog/tog23.html#SederbergCFNZL04