@Article{jue:11f,
  author =   {M. Byrtus and M. Kapl and B. J\"uttler},
  title =    {Triangular Bubble Spline Surfaces},
  journal =  {Computer-Aided Design},
  volume =   {43},
  year =     {2011},
  pages =    {1341-1349},
  DOI = {10.1016/j.cad.2011.08.021}}