Nielsen, L. (2011). Classifications of Countries Basedon their Level of Development: How it is Done and How it Could Be Done. International Monetary Fund.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Nielsen, Lynge. Classifications of Countries Basedon Their Level of Development: How It Is Done and How It Could Be Done. Washington, D.C.: International Monetary Fund, 2011.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Nielsen, Lynge. Classifications of Countries Basedon Their Level of Development: How It Is Done and How It Could Be Done. International Monetary Fund, 2011.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.