Al Hashash، A. A. J.، و Netusil، A. J. (1981). Investigation of Students Study Habits Under Traditional and Phase Achievement Systems of Instruction in A College Biology Course (رسالة دكتوراه غير منشورة). Iowa State University، آيوا. مسترجع من http://search.mandumah.com/Record/611147
Al Hashash، Abd Allatif Jassim، و Anton J. Netusil. "Investigation of Students Study Habits Under Traditional and Phase Achievement Systems of Instruction in A College Biology Course" رسالة دكتوراه. Iowa State University، آيوا، 1981. مسترجع من http://search.mandumah.com/Record/611147