@InProceedings {Oltmans2004ETCHASketch,
  author =       {Michael Oltmans and Christine Alvarado and Randall Davis},
  title =        {ETCHA Sketches: Lessons Learned from Collecting Sketch Data},
  booktitle =    {Making Pen-Based Interaction Intelligent and Natural},
  year =         {2004},
  publisher =    {AAAI Fall Symposium},
  OPTkeyword =   {general sketch recognition}
}