References Sapere.itSapere.it. Enciclopedia
; AGROVOCFAO <Food and Agriculture Organization of the United Nations> AGROVOC Multilingual thesaurus
; ; CABCommonwealth agricultural bureaux International, CAB Thesaurus
; ; ; ; ; Wikipedia(IT)Wikipedia. L'enciclopedia libera, 2001 [ed. in lingua italiana dell' enciclopedia online Wikipedia]
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