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De Vos, Paula (2006). "The Science of Spices: Empiricism and Economic Botany in the Early Spanish Empire". Journal of World History. 17 (4): 399–427. doi:10.1353/jwh.2006.0054. JSTOR20079398. S2CID201793405.
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De Vos, Paula (2006). "The Science of Spices: Empiricism and Economic Botany in the Early Spanish Empire". Journal of World History. 17 (4): 399–427. doi:10.1353/jwh.2006.0054. JSTOR20079398. S2CID201793405.
Stevens, Mikel, Jeff Maughan, and Rick Jellen. "Domestication of Corn, Rice, Soybean, and Sugarbeet." Living with Plants. July 08 2003. May 2009. <"Domestication of Corn". Archived from the original on 2009-02-03. Retrieved 2009-05-06.>.