PME 21: Proceedings of the 21st Conference of the International Group for the Psychology of Mathematics Education : July 14-19, 1997, Lanti, Finland Erkki Pehkonen University of Helsinki, Lahti Research and Training Centre, 1997 |
PME 21: Proceedings of the 21st Conference of the International Group for the Psychology of Mathematics Education : July 14-19, 1997, Lanti, FinlandErkki Pehkonen University of Helsinki, Lahti Research and Training Centre, 1997 |