Mathematics Teaching, Vol. 82 (1978), pp. 44-49.
(2003)
(2003)
Vol. 2 (1993), pp. 41-48.
(2004)
Journal of Mathematical Behavior, Vol. 5 (1986), pp. 281-303.
Journal of Mathematical Behavior, Vol. 15 (1996), pp. 167-192.
(1991), pp. 153-166.
Educational Studies in Mathematics, Vol. 60, No. 2. (October 2005), pp. 253-266.
Educational Studies in Mathematics, Vol. 60, No. 3. (November 2005), pp. 269-295.
International Journal of Computers for Mathematical Learning, Vol. 3, No. 3. (1999), pp. 195-227.
(1999)
Proceedings of the 25th PME Conference, Vol. 3 (2001), pp. 241-248.
Educational Studies in Mathematics, Vol. 22 (1991), pp. 1-36.
Canadian Journal of Science, Mathematics and Technology Education (2003)
International Journal of Computers for Mathematical Learning, Vol. 7, No. 3. (2002), pp. 245-275.
Educational Studies in Mathematics, Vol. 39, No. 1-3. (July 1999), pp. 45-65.
Mathematical Cognition, Vol. 4, No. 2. (1 September 1998), pp. 85-101.