@Article{	  Beuchler:2005*1,
  author	= {Beuchler, S.},
  title		= {Extension operators on tensor product structures in two
		  and three dimensions},
  journal	= {SIAM J. Sci. Comput.},
  fjournal	= {SIAM Journal on Scientific Computing},
  volume	= {26},
  year		= {2005},
  number	= {5},
  pages		= {1776--1795}
}