توثيق جمعية علم النفس الأمريكية APA (الطبعة السابعة)

Collier, P. (2007). The bottom billion: Why the poorest countries are failing and what can be done about it. Oxford University Press.

توثيق أسلوب شيكاغو (الطبعة السابعة عشر)

Collier, Paul. The Bottom Billion: Why the Poorest Countries Are Failing and What Can Be Done About It. Oxford ; New York: Oxford University Press, 2007.

توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)

Collier, Paul. The Bottom Billion: Why the Poorest Countries Are Failing and What Can Be Done About It. Oxford University Press, 2007.