@InProceedings{Lee07b,
  author    = {WeeSan Lee and Ruwanee de Silva and Eric J. Peterson and
               Robert C. Calfee and Thomas F. Stahovich},
  title     = {Newton's Pen - A Pen-based Tutoring System for Statics},
  booktitle = {2007 Eurographics Workshop on Sketch-Based Interfaces and
               Modeling},
  pages     = {59-66},
  month     = {August},
  year      = {2007},
}