Approximating curves and their offsets using biarcs and Pythagorean hodograph quintics. - Zbynek Sír; Robert Feichtinger; Bert Jüttler (Comput. Aided Des., 2006)

Dual evolution of planar parametric spline curves and T-spline level sets. - Robert Feichtinger; Matthias Fuchs; Bert Jüttler; Otmar Scherzer; Huaiping Yang (Comput. Aided Des., 2008)