3Belcher J W, Dourmashkin P, Litster D. http://gallery. carnegiefoundation, org/collections/keep/jbeleher/.
4Cummings K, Marx J, Sornton R, et al. Evaluating Innovations in Studio Physits, Physics Educational Research[J]. American Journal of Physics, Suppl. 1999,67 : S38- S45.