1. NCTM 1994 Yearbook,1994
2. D’Ambrosio, Ubiratan: 1979, ‘Overall goals and objectives for mathematical education’, in UNESCO: New trends in mathematics teaching, Volume IV, Paris: Unesco, pp. 180–198
3. Bachmann, Friedrich: 1971, ‘n-Gons’ Educational Studies in Mathematics
3 pp. 288–309
4. Balacheff, Nicolas: 1980, ‘Une étude, a l’aide des graphes, de démonstrations mathématiques formulées par des élèves’, Educational Studies in Mathematics
11, pp.91–111
5. Bauersfeld, Heinrich: 1980, ‘Hidden Dimensions in the So-Called Reality of a Mathematics Classoom’, Educational Studies in Mathematics
11, pp.23–41