3R. J. Dufresne,W. J. Gerace, W. J. Leonard, J. P. Mestre, and L. Wenk. Classtalk: A classroom communication system for active learning[J]. Journal of Computing Higher Education, 1996(7): 3-47.
4I. D. Beatty. Transforming student learning with classroom communication systems [DB/OL]. http://arxiv.org/ftp/physics/papers/0508/ 0508129.pdf.
5Ian D. Beatty, William J. Gerace, William J. Leonard, and Robert J. Dufresne. Designing effective questions for classroom response system teaching[J]. American Journal of Physics. 2006(1): 31-39.
