Freeman, D. B. (1973). International trade, migration, and capital flows: A quantitative analysis of spatial economic interaction. University of Chicago, Dept. of Geography].
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Freeman, Donald B. International Trade, Migration, and Capital Flows: A Quantitative Analysis of Spatial Economic Interaction. [Chicago: University of Chicago, Dept. of Geography], 1973.
توثيق جمعية اللغة المعاصرة MLA (الإصدار التاسع)Freeman, Donald B. International Trade, Migration, and Capital Flows: A Quantitative Analysis of Spatial Economic Interaction. University of Chicago, Dept. of Geography], 1973.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.