@inproceedings{zeng2009c,
  title={C^\infty smooth freeform surfaces over hyperbolic domains},
  author={Zeng, Wei and He, Ying and Xia, Jiazhi and Gu, Xianfeng and Qin, Hong},
  booktitle={2009 SIAM/ACM Joint Conference on Geometric and Physical Modeling},
  pages={367--372},
  year={2009},
  organization={ACM}
}