1. Carpenter T. P. Franke M. L. and Levi L. (2003). Thinking mathematically: integrating arithmetic and algebra in the elementary school. Portsmouth NH: Heinemann. Carpenter T. P. Franke M. L. and Levi L. (2003). Thinking mathematically: integrating arithmetic and algebra in the elementary school . Portsmouth NH: Heinemann.
2. “Concrete” Computer Manipulatives in Mathematics Education
3. Using the Number-Line to Investigate the Solving of Linear Equations;Dickinson P.;The Learning of Mathematics,2004
4. How Emergent Models May Foster the Constitution of Formal Mathematics