exports to GDP in the USA 1800-60: Susan B. Carter, Scott Sigmund Gartner, Michael R. Haines, Alan L. Olmstead, Richard Sutch, and Gavin Wright,

Historical Statistics of the United States , millenium edition, online (Cambridge University Press), series Ca10 and Ee366.

de-industrialization in Puebla: von Humboldt,

, Vol. III, p. 469.

scientific culture and education in Mexico: von Humboldt,

, Vol. I, pp. 212, 216, 223.

الفصل السابع: أفريقيا

French Congo: Jacqueline M. C. Thomas,

Les Ngbaka de la Lobaye: le dépeuplement rural chez une population forestière de la République Centrafricaine (Mouton, 1963), pp. 258-71, 417-19.

the spirits of traders: Mary Kingsley,

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