Costello, M. A. (1989). Levels of living and their geographic context: Northern Mindanao, 1960-1980. Population/Development Planning and Research Project.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Costello, Michael A. Levels of Living and Their Geographic Context: Northern Mindanao, 1960-1980. [Makati, Metro Manila]: Population/Development Planning and Research Project, 1989.
توثيق جمعية اللغة المعاصرة MLA (الإصدار التاسع)Costello, Michael A. Levels of Living and Their Geographic Context: Northern Mindanao, 1960-1980. Population/Development Planning and Research Project, 1989.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.