geometry

Lehrer, R. &Chazan, D. (Eds). (1998). Designing learning environments for developing understanding of geometry and space. Hilldale, NJ: LEA.
Mammana, C. & Villani, V. (Eds.). (1998). Perspectives on the teaching of geometry for the 21st century: A ICMI study. Dordrecht: Kluwer Academic Publishers.