Viseu, Floriano, Ana Luisa Pires, Luís Menezes, and Ana Maria Costa. “Semiotic Representations in The Learning of Rational Numbers by 2nd Grade Portuguese Students”. International Electronic Journal of Elementary Education 13, no. 5 (July 14, 2021): 611–624. Accessed April 21, 2025. https://iejee.com/index.php/IEJEE/article/view/1453.