Zainol bin Ahmed. (2015). Identifying the factors affecting the performance of building maintenance contractors: A case study of Perkeso building in Klang Valley. Kulliyyah of Architecture and Environmental Design, International Islamic University Malaysia.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Zainol bin Ahmed. Identifying the Factors Affecting the Performance of Building Maintenance Contractors: A Case Study of Perkeso Building in Klang Valley. Kuala Lumpur: Kulliyyah of Architecture and Environmental Design, International Islamic University Malaysia, 2015.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Zainol bin Ahmed. Identifying the Factors Affecting the Performance of Building Maintenance Contractors: A Case Study of Perkeso Building in Klang Valley. Kulliyyah of Architecture and Environmental Design, International Islamic University Malaysia, 2015.