1. R. Lesh, T. Post and M. Behr. “Number Concepts and Operations in the Middle Grades” in J. Hiebert & M. Behr (Eds.) (Reston, VA: Lawrence Erlbaum & National of Teachers of Mathematics). pp. 93–118. Available at: http://www.cehd.umn.edu/ci/rationalnumberproject/88_8.html;
2. S. Lamon. “Teaching fractions and ratios for understanding: Essential content knowledge and instructional strategies for teachers. Mahwah.” (NJ: Lawrence Erlbaum). 1999.
3. J. Kilpatrick, J. Swaford and B. Findel. “Adding it up: Helping children learn mathematics.” (Washington DC: National Academy Press). 2001.
4. S. Dole. “Making connections to the big ideas in mathematics: Promoting proportional reasoning. In: Carolyn Glascodine and Kerry-Anne Hoad, Teaching Mathematics? Make it count: What research tells us about effective mathematics teaching and learning.” (Paper presented at ACER Research Conference 2010, Melbourne, VIC, Australia, 15-17 August 2010), p. 71–74.
5. Early adolescents' proportional reasoning on ?rate? problems