@inproceedings{Prautzsch1998Analysis,
  Author = {Hartmut Prautzsch},
  Title = {Analysis of C<sup>k</sup>-Subdivision surfaces at extraordinary points},
  Booktitle = {},
  Year = {1998},
  Note = {Interner Bericht 98/4, Fakultät f{"u}r Informatik, Universität Karlsruhe}
}