8Malofeeva E, Day J, Saco X, et al. Construction and evaluation of a number sense test with Head Start children. Journal of Educational Psychology, 2004, 96(4), 648- 659.
9Beswick K, Muir T, McIntosh A J. Developing an instrument to assess the number sense of young children. AARE 2004 International Education Research Conference Paper, Melbourne, Australia, 2004, 1 - 12. http:// www. aare. edu. au/04pap/bes04625.pdf.
10Reys R, Reys B, McIntosh A, et al. Assessing number sense of student in Australia, Sweden, Taiwan, and the United States. School Science and Mathematics, 1999, 99(2): 61 - 70.