@article{etna_vol18_pp42-48,
  author  = {Susanne C. Brenner},
  title   = {Discrete Sobolev and Poincar\'e inequalities for piecewise polynomial functions},
  journal = {Electron. Trans. Numer. Anal.},
  volume  = {18},
  year    = {2004},
  pages   = {42--48},
}