@inproceedings{Prautzsch1996Multivariate,
  Author = {Hartmut Prautzsch},
  Title = {Multivariate Splines with convex B-patch control nets are convex},
  Booktitle = {},
  Year = {1996},
  Note = {In: Hoschek, Kaklis (eds.), Advanced Course on Fairshape, Teubner,1996: 153-159}
}