@ARTICLE{OhRu99,
  author = {Ohlberger, M. and Rumpf, M.},
  title = {Adaptive Projection Operators in Multiresolutional Scientific Visualization},
  journal = {IEEE Transactions on Visualization and Computer Graphics},
  year = {1999},
  volume = {5-1},
  pages = {74--94},
  number = {4},
  pdf = {http://numod.ins.uni-bonn.de/research/papers/public/OhRu99.pdf}
}