Não informado. (1961). Illinois agricultural economics. University of Illinois, Department of Agricultural Economics.
শিকাগো স্টাইল (17 তম সংস্করণ) উদ্ধৃতিNão informado. Illinois Agricultural Economics. Urbana, Ill: University of Illinois, Department of Agricultural Economics, 1961.
M.L.A (8 ম সংস্করণ) উদ্ধৃতিNão informado. Illinois Agricultural Economics. University of Illinois, Department of Agricultural Economics, 1961.
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