Não informado. (1961). Illinois agricultural economics. University of Illinois, Department of Agricultural Economics.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Illinois Agricultural Economics. Urbana, Ill: University of Illinois, Department of Agricultural Economics, 1961.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Illinois Agricultural Economics. University of Illinois, Department of Agricultural Economics, 1961.
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