@InCollection{Hammond2004LadderAbstract,
  author =       {Tracy Hammond and Randall Davis},
  title =        {LADDER: A Sketch Recognition Language},
  booktitle =    {MIT Computer Science and Artificial Intelligence Laboratory Annual Research Abstract},
  publisher =    {MIT CSAIL},
  year =         2004,
  month =        {September},
  keywords =     {multimodal}
}