توثيق جمعية علم النفس الأمريكية APA (الطبعة السابعة)

Hamzah Umar. (2002). Causes of visual impairment among students attending schools for the blind in Kedah, Malaysia. Universiti Kebangsaan Malaysia.

توثيق أسلوب شيكاغو (الطبعة السابعة عشر)

Hamzah Umar. Causes of Visual Impairment Among Students Attending Schools for the Blind in Kedah, Malaysia. Kuala Lumpur: Universiti Kebangsaan Malaysia, 2002.

توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)

Hamzah Umar. Causes of Visual Impairment Among Students Attending Schools for the Blind in Kedah, Malaysia. Universiti Kebangsaan Malaysia, 2002.