@InProceedings{chen-rfd-cgi,
        author = {Xianming Chen and Richard F. Riesenfeld and  Elaine Cohen},
        title = {Rational {B}\'{e}zier Patch Differentiation using the Rational Forward Difference Operator},
        Booktitle = "Proceedings of IEEE Computer Graphics International 2005",
        Year = 2005,
        pages={129-134},
}