1. Adinawan, M. C., & Sugijono, S. (2007). Matematika untuk SMP kelas VII semester 1. [Mathematics for junior secondary school grade VII semester 1.] Jakarta: Erlangga.
2. Arcavi, A. (1994). Symbol sense: informal sense-making in formal mathematics. For the Learning of Mathematics, 25(2), 24–35.
3. Arcavi, A. (2005). Developing and using symbol sense in mathematics. For the Learning of Mathematics, 14(3), 42–47.
4. Bokhove, C., & Drijvers, P. (2010). Symbol sense behavior in digital activities. For the Learning of Mathematics, 30(3), 43–49.
5. Bokhove, C. (2011). Use of ICT for acquiring, practicing, and assessing algebraic expertise. Dissertation. Utrecht: Utrecht University.