A. Waraich. ITiCSE '04: Proceedings of the 9th annual SIGCSE conference on Innovation and technology in computer science education, page 97-101. New York, NY, USA, ACM, (2004)
A. Sfard. Proceedings of 21st Conference of PME-NA, page 23-44. Columbus, Ohio, Clearing House for Science, mathematics, and Environmental Education, (2001)
F. Arzarello. the 24th Conference of the International Group for the Psychology of Mathematics Education (PME), 1, page 23--38. Hiroshima, Japan, (2000)
C. Sackur, T. Assude, and M. Maurel. European Research in Mathematics Education I.I + I.II Proceedings of the First Conference of the European Society for Research in Mathematics Education, 1 & 2, Osnabrueck, Forschungsinstitut fuer Mathematikdidaktik, (1999)