@ARTICLE{CrePenPip98,
  AUTHOR =       {P. Crescenzi and P. Penna and A. Piperno},
  TITLE =        {Linear Area Upward Drawings of {AVL} Trees},
  JOURNAL =      {Computational Geometry: Theory and Applications},
  YEAR =         {1998},
  volume =       {9},
  number =       {1-2},
  pages =        {25-42}
}