@article{etna_vol35_pp257-280,
  author  = {Howard C. Elman and Ray S. Tuminaro},
  title   = {Boundary conditions in approximate commutator preconditioners for the Navier-Stokes equations},
  journal = {Electron. Trans. Numer. Anal.},
  volume  = {35},
  year    = {2009},
  pages   = {257--280},
}