1. Cai, Jinfa, Hee Chan Lew, Anne Morris, John C. Moyer, Swee Fong Ng, and Jean Schmittau. (2005) “The Development of Students’ Algebraic Thinking in Earlier Grades: A Cross-Cultural Comparative Perspective”. Zentralblatt fuer Didaktik der 37 pp. 5-15.
2. Cai Jinfa & John Moyer (2008). Developing Algebraic Thinking in Earlier Grades: Some Insights from International Comparative Studies, National Council of Teachers of Mathematics, Yearbook.
3. Developing Algebraic Thinking in Early Grades: Case Study of Korean Elementary School Mathematics;Hee-Chan Lew;the Mathematics Educator,2004
4. Herbert Kristen & Rebacca Brown (2000). Patterns as Tools for Algebraic Reasoning, National council of teachers of mathematics, Reston, VA: Author, pp 123-128.