HATEM , A. . .; EBRAHEEM, K. . . Effectiveness of Universal Concept of Mental Arithmetic System (UCMAS) In The Developing Of Visual Thinking Among Fourth Grade Students (Quasi- Experimental Study In Private Schools At Lattakia). Tishreen University Journal- Arts and Humanities Sciences Series, [S. l.], v. 38, n. 1, 2017. Disponível em: https://journal.tishreen.edu.sy/index.php/humlitr/article/view/2318. Acesso em: 22 may. 2024.