@ARTICLE{XieYu:SmoothnessEquiv,
  author =       {G. Xie and T. P.-Y. Yu},
  title =        {Smoothness Equivalence Properties of
                  Manifold-Valued Data Subdivision Schemes based on the Projection Approach},
  journal =      {{S}{I}{A}{M} Journal on Numerical Analysis},
  year =         {2007},
  volume =       {45},
  number =       {3},
  pages =        {1200-1225},
}