MUSTAPHA AL- HARBAWI, K. Level of Difficulty in Teaching Mathematics at the secondary Stage in the Light Reforming the Curriculum and its teachers’ Point of view. College of Basic Education Research Journal, [S. l.], v. 13, n. 2, p. 1–40, 2014. Disponível em: https://stats.uomosul.edu.iq/index.php/berj/article/view/39291. Acesso em: 26 oct. 2025.