@InProceedings{deSilva07,
  author    = {Ruwanee de Silva and David Tyler Bischel and WeeSan Lee and
               Eric J. Peterson and Thomas F. Stahovich and Robert Calfee},
  title     = {Kirchhoff's Pen: A Pen-based Circuit Analysis Tutor},
  booktitle = {2007 Eurographics Workshop on Sketch-Based Interfaces and
               Modeling},
  pages     = {75-82},
  month     = {August},
  year      = {2007},
}