@inproceedings{Prautzsch1992Simple, Author = {Hartmut Prautzsch and Wilfried Trump}, Title = {Simple surfaces have no simple C1 parametrization}, Booktitle = {}, Year = {1992}, Note = {In: T. Lyche, L.L. Schumaker (eds.), Mathematical Methods in CAGD II, Academic Press, 1992: 475-480} }