*Mohamed El-Demerdash (2003). The Role of Concrete Manipulative Materials in Improving Achievement Level of Visually Handicapped Pupils in Mathematics. Master's thesis, Damietta faculty of Education, Mansoura University, Egypt. | *Mohamed El-Demerdash (2003). The Role of Concrete Manipulative Materials in Improving Achievement Level of Visually Handicapped Pupils in Mathematics. Master's thesis, Damietta faculty of Education, Mansoura University, Egypt. |