@article{etna_vol8_pp46-87,
  author  = {Ingemar Persson and Klas Samuelsson and Anders Szepessy},
  title   = {On the convergence of multigrid methods for flow problems},
  journal = {Electron. Trans. Numer. Anal.},
  volume  = {8},
  year    = {1999},
  pages   = {46--87},
}