1. Determination and classification of triangular quadric patches;Albrecht;Computer Aided Geometric Design,1998
2. Self-intersection of an offset surface;Aomura;Computer-Aided Design,1990
3. Quadric splines;Bangert;Computer Aided Geometric Design,1999
4. Béezier patches on quadrics;Boehm,1991
5. Quadratic forms and their classification by means of invariant-factors;Bromwich,1906