GREENFIELD, Amy Butler. A Perfect Red – Empire, Espionage and the Qest for the Color of Desire. New York: HarperCollins, 2004. Dostupné online. ISBN0-06-052275-5. S. 29.
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Kerria Targioni Tozzetti [online]. United States Department Of Agriculture, Agriculture Research Service [cit. 2012-07-09]. Dostupné v archivu pořízeném dne 2012-12-14. (anglicky)