1. Arzarello F.(2006).Semiosis as multimodal process.Revista Latinoamericana de Investigación en Matemática Educativa Special edition 267–299.
2. Arzarello F. Ferrara F. Robutti O.(2011).A tool for analyzing multimodal behaviours in the mathematics classroom. InProceedings of the 33th Conference of the International Group for the Psychology of Mathematics Education PME volume 2 Ankara.