1. AAAS (2000): Algebra for all: Not with today's texbooks. See www.project2061.org/newsinfo/press/r1000426.htm
2. Cai, J. (2004a): Introduction to the special issue on developing algebraic thinking in the earlier grades from an international perspective.—In: The Mathematics Educator (Singapore), 8(No.1), p. 1–5
3. Cai, J. (2004b): Developing algebraic thinking in the earlier grades: A case study of the Chinese mathematics curriculum. —In: The Mathematics Educator (Singapore), 8(No. 1), p. 107–130
4. Carpenter, T. P.; Franke, M. L.; Levi, L. (2003): Thinking mathematically: Integrating arithmetic and algebra in elementary school. Portsmouth, NH: Heinemann
5. Curriculum Planning & Development Division (2000): Mathematics syllabus primary.—Singapore: Ministry of Education