مهدي يونس الخفاجي و. “The Impact of Using Introductory Problems Solving on the Achievement of Fifth Primary Female Pupils and Developing Their Deductive Thinking”. College of Basic Education Research Journal, vol. 8, no. 4, Dec. 2009, pp. 1-36, https://jeh.uomosul.edu.iq/index.php/berj/article/view/39904.